BOX STOCK CLASS REGULATIONS

DRIVER RESTRICTIONS

• Lipo 3500, 2wd Mod, AWD Mod, Lipo 2500 Pan, or Open Pan drivers are not permitted in Box Stock class.

CHASSIS

• Allowed: Kyosho MR03S, MR03S2, MR03 RTR, MR04 RWD, Associated SR27 (RWD only)
• Not Allowed:Shaving chassis or removing sections for weight reduction
• Chassis must be raced as manufactured from the box

WHEELBASE

• Only allowed wheelbases: RWD 90mm, 94mm, 98mm, and 102mm

MOTOR & ESC BOARD

• Kyosho MZ9P, MZ9E Motor from RWD RTR
• Permitted modifications:
  • Changing motor wires with same or maximum (20) gauge wire 
  • Removing safety switch
  • Motor must be run as manufactured with no other manipulations or modifications
• Not Permitted: EVO Board or other upgraded board

GEAR RATIO

• 6T - 9T Pinion (included with RTR kits)
• Stock Kyosho Gear Diff only

WHEELS

• All brand plastic and aluminum 1/28 scale production wheels allowed
• Size limitations:
  • Maximum front-wheel width: 8.5mm (not including outer flange/disk)
  • Maximum rear-wheel width: 11mm (not including outer flange/disk)
  • Maximum wheel diameter: 20mm
  • Minimum wheel diameter: 19mm
• Wheels must be original designs made for 1/28 scale cars
• Wheel and tire must fit inside the body

TIRES

• Maximum tire diameter (mounted): 25.5mm
• Front tires must be 8.5mm and rear tires 11mm
• Not Allowed:
  • Traction compound on tire or race surface
  • Tire warmers
  • Homemade tires
  • Foam tires
  • Silicon tires
  • Urethane tires
  • Ethyl Carbonate tires
  • Tire inserts
• Tires may be cleaned with 70% alcohol solution or water
• Using illegal tire cleaner will result in penalties
• Direct tire-related questions to the driver's meeting or race director

BATTERIES

• Cars must be powered by 4 AAA batteries
• Allowed types: Alkaline, Ni-MH, or Ni-Cd
• An additional battery is allowed only for transponder connection

ELECTRONICS & TRANSMITTER

• Stock Radio from RTR Kit
• Only Kyosho original items included in the RTR box are allowed
• No modifications to radio permitted

BODY

• Any manufactured molded hard shell that fits the allowed wheelbase
• All parts must be original for that body
• Limited wheel and ground clearance modifications allowed
• Size limitations:
• Maximum body length: 180mm
• Maximum width: 83mm
• Not Allowed:
  • Shaving/thinning body material for weight reduction
  • Lexan roofs, windows, and wings
• Headlight requirements:
  • Original headlight covers must be installed
  • Headlight buckets may be removed/omitted
  • Lost headlight covers may be replaced with decal/tape
• Taillights and covers may be removed/omitted
• Small body parts (mirrors, canards, exhausts, front splitters) may be omitted to prevent racing damage
• Wings: Standard rear wings for corresponding hard-shell body may be used with no height limit
• Custom aftermarket plastic wings must meet 45mm height limit from ground

OPTION PARTS

• Allowed from any manufacturer: bearings, wheel nuts, springs, and T-Plates
• Only original Kyosho front and rear suspension parts may be used
• No added weight via tungsten, brass, or other materials

MODIFICATIONS

• King pin flip allowed, lower pin must be shortened to no damage track

AAA 3500 CLASS REGULATIONS

CHASSIS

• Allowed models: Kyosho MR03S, MR03S2, & MR03 RWD, MR04 RWD, Jomurema, MRC MRC01, PN PNR2.5W

WHEELBASE

• Only allowed wheelbases: 90mm, 94mm, 98mm, and 102mm

MOTOR

• Any manufacturer 3500Kv motor ( must run sensorless- no sensor wires attached)
• Maximum can diameter: 15mm
• Maximum Kv: 3800
• No aftermarket rotors allowed
• Motors must not be tampered with or modified

GEAR RATIO

• Any manufacturer pinion and spur allowed
• Tooth count must be distinguishable by markings or color for easy tech
• All gears must be Pre-Event teched and painted
• Standard ratio: 53T Spur, 16T pinion (unless specified for track conditions by event)

WHEELS

• All brand plastic and aluminum 1/28 scale production wheels allowed
• Size limitations:
  • Maximum front-wheel width: 8.5mm (not including outer flange/disk)
  • Maximum rear-wheel width: 11mm (not including outer flange/disk)
  • Maximum wheel diameter: 20mm
  • Minimum wheel diameter: 19mm
• Wheels must be original designs made for 1/28 scale cars
• Wheel and tire must fit inside the body

TIRES

• Maximum tire diameter (mounted): 25.5mm
• Front tires must be 8.5mm and rear tires 11mm
• Tire warmers are allowed
• Tires may be cleaned with 70% alcohol solution or water
• Not Allowed: 
  • Traction compound on tire or race surface
  • Homemade tires
  • Foam tires
  • Silicon tires
  • Urethane tires
  • Ethyl Carbamate tires
  • Tire inserts
• Using illegal tire cleaner will result in penalties

BATTERIES

• Cars must be powered by 4 AAA batteries
• Allowed types: Alkaline, Ni-MH, or Ni-Cd
• An additional battery is allowed only for transponder connection

ESC / RECEIVER

• Any 1/28th scale MiniZ ESC and Receiver in the same flat board configuration as the Kyosho EVO board
• Not Allowed:
  • Receivers with built-in Gyro
  • Separate Gyros

BODY

• Any manufactured molded hard shell that fits the allowed wheelbase
• All parts must be original for that body
• Limited wheel and ground clearance modifications allowed
• Lexan roofs, windows, and wings are allowed
• Size limitations:
  • Maximum body length: 180mm
  • Maximum width: 83mm
  • Minimum Weight: 24 grams
• Headlight requirements: Original headlight covers must be installed
• Headlight buckets may be removed/omitted
• Lost headlight covers may be replaced with decal/tape
• Taillights and covers may be removed/omitted
• Small body parts (mirrors, canards, exhausts, front splitters) may be omitted to prevent racing damage
• Wings: Standard rear wings for corresponding hard-shell body may be used with no height limit
• Custom aftermarket plastic wings must meet 45mm height limit from ground

WEIGHT

• Full car minimum weight: 160 grams (race ready)

OPTIONAL PARTS

• Any aftermarket 1/28 scale publicly available production or 3D printed parts allowed
• Adding weight via tungsten putty, stick weight, or cut hobby brass is allowed
• Not Allowed: Prototype parts
• Public availability requirements: Parts must be publicly announced via social media or website 45 days prior to race
• Parts must be available for purchase nationally 45 days prior to race
• 3D print files must be shared with the public 30 days before event start

Any questions concerning class rules should be addressed at the driver's meeting or with the race director.

 

LIPO 2500 CLASS 

• Allowed models: Kyosho MR03S, MR03S2, & MR03 RWD, Jomurema, GL Racing GLR, GLR-GT, GL-GTR, MRC MRC01, PN PNR2.5W, PNR3.0, RTRC RTA, Atomic MRZ, MRX, MRV, RX28/SE G1, G2 and G3, NEXX Skyline, Specter, MWX R.1, G-Force Lightning, XBility XB 1, AE RC28

WHEELBASE

• Only allowed wheelbases: 98mm and 102mm

MOTOR

• Any 1/28th scale manufacturer 2500Kv sensored motor
• Maximum can diameter: 15mm
• Maximum Kv: 2800
• No aftermarket rotors allowed
• Motors must not be tampered with or modified

GEAR RATIO

• Any manufacturer pinion and spur allowed
• Tooth count must be distinguishable by markings or color for easy tech
• All gears must be Pre-Event teched and painted
• Standard ratio: 12T Pinion / 53T Spur (unless specified for track conditions by event)

WHEELS

• All brand plastic and aluminum 1/28 scale production wheels allowed
• Size limitations:
  • Maximum front-wheel width: 8.5mm (not including outer flange/disk)
  • Maximum rear-wheel width: 11mm (not including outer flange/disk)
  • Maximum wheel diameter: 20mm
  • Minimum wheel diameter: 19mm
• Wheels must be original designs made for 1/28 scale cars
• Wheel and tire must fit inside the body

TIRES

• Maximum tire diameter (mounted): 25.5mm
• Front tires must be 8.5mm and rear tires 11mm wide
• Tire warmers are allowed
• Tires may be cleaned with 70% alcohol solution or water
• Not Allowed:
  • Traction compound on tire or race surface
  • Homemade tires
  • Foam tires
  • Silicon tires
  • Urethane tires
  • Ethyl Carbamate tires
  • Tire inserts
• Using illegal tire cleaner will result in penalties

BATTERIES

• 2-cell LiPo or 2 one-cells paralleled (maximum 8.40 volts)
• Max battery dimensions 45 x 24.0 x 13.0mm
• Battery must be identifiable with original sticker from 1/28th MiniZ manufacturer
• Maximum 500 mAh
• An additional battery is allowed only for transponder connection

ESC / RECEIVER

• Any manufacturer 1/28 ESC and Receiver allowed
• ESC must not have any timing, turbo or boost activated and have a visual Blinking LED. (Blinky Mode) LED. (Blinky Mode) 
• Not Allowed:
  • Receivers with built-in Gyro
  • Separate Gyros

BODY

• Any manufactured molded hard shell that fits the allowed wheelbase
• All parts must be original for that body
• Limited wheel and ground clearance modifications allowed
• Lexan roofs, windows, and wings are allowed
• Size limitations:
  • Maximum body length: 180mm
  • Maximum width: 83mm
  • Minimum Weight: 24 grams
• Headlight requirements: Original headlight covers must be installed
• Headlight buckets may be removed/omitted
• Lost headlight covers may be replaced with decal/tape
• Taillights and covers may be removed/omitted
• Small body parts (mirrors, canards, exhausts, front splitters) may be omitted to prevent racing damage
• Wings: Standard rear wings for corresponding hard-shell body may be used with no height limit
• Custom aftermarket plastic wings must meet 45mm height limit from ground

OPTIONAL PARTS

• Any aftermarket 1/28 scale publicly available production or 3D printed parts allowed
• Adding weight via tungsten putty, stick weight, or cut hobby brass is allowed
• Not Allowed:
  • Prototype parts
• Public availability requirements:
• Parts must be publicly announced via social media or website
• Parts must be available for purchase nationally 45 days prior to race
• 3D print files must be shared with the public 30 days before event start

WEIGHT

• Full car minimum weight: 160 grams (race ready)

Any questions concerning class rules should be addressed at the driver's meeting or with the race director.

FORMULA 1 CLASS REGULATIONS

CHASSIS

• Allowed models: GL Racing GLF-1, G-Force Formula, PNR 3.0F1, MWX R1F1, Atomic SF-F1 conversion, Reflex FX28

WHEELBASE

• Only allowed wheelbase: 112mm – 116mm

MOTOR

• Any 1/28th scale manufacturer 2500Kv sensored motor
• Maximum can diameter: 15mm
• Maximum Kv: 2800
• No aftermarket rotors allowed
• Motors must not be tampered with or modified

GEAR RATIO

• Any manufacturer pinion and spur allowed
• Tooth count must be distinguishable by markings or color for easy tech
• All gears must be Pre-Event teched and painted
• Standard ratio: 12T Pinion / 53T Spur (unless specified for track conditions by event)

WHEELS

• All brand plastic and aluminum 1/28 scale production wheels allowed
• Size specifications:
• Front-wheel width: 11mm
• Rear-wheel width: 14mm (not including outer flange/disk)
• Maximum wheel diameter: 20mm
• Minimum wheel diameter: 19mm
• Wheels must be original designs made for 1/28 scale cars

TIRES

• Maximum tire diameter (mounted): 25.5mm
• Front tires must be 11mm and rear tires 14mm wide
• Tire warmers are allowed
• Tires may be cleaned with 70% alcohol solution or water
• Not Allowed:
  • Traction compound on tire or race surface
  • Homemade tires
  • Foam tires
  • Silicon tires
  • Urethane tires
  • Ethyl Carbamate tires
• Tire inserts
• Using illegal tire cleaner will result in penalties

BATTERIES

• 2-cell LiPo or 2 one-cells paralleled (maximum 8.4 volts)
• Max battery dimensions 45 x 24.0 x 13.0mm
• Battery must be identifiable with original sticker from 1/28th MiniZ manufacturer
• Maximum 500 mAh
• An additional battery is allowed only for transponder connection

ESC / RECEIVER

• Any manufacturer ESC and Receiver allowed
• ESC must have and be in BLINKY MODE
• Not Allowed:
  • Receivers with built-in Gyro
  • Separate Gyros

BODY

• Lexan F1 Bodies only: GLF-1, PN-F1, MWX, G-Force, Reflex FX28
• Aftermarket front and rear wings allowed (must look like an F1 wing)
• Bearings in the front wing are not allowed

OPTION PARTS

• Any aftermarket 1/28 scale publicly available production or 3D printed parts allowed
• Adding weight via tungsten putty, stick weight, or cut hobby brass is allowed
• Not Allowed:
  • Prototype parts
• Public availability requirements:
• Parts must be publicly announced via social media or website
• Parts must be available for purchase nationally 45 days prior to race
• 3D print files must be shared with the public 30 days before event start

WEIGHT

• Minimum weight: 140 grams

Any questions concerning class rules should be addressed at the driver's meeting or with the race director.

LIPO 3500 LEXAN CLASS REGULATIONS

CHASSIS

• Allowed models: Kyosho MR03S, MR03S2, and MR03 RWD, Jomurema, GL Racing GLR, GLR-GT, GL-GTR, MRC MRC01, PN PNR2.5W, PNR3.0, RTRC RTA, Atomic MRZ, MRX, MRV, RX28/SE G1, G2 and G3, NEXX Skyline, Specter, MWX R.1, G-Force Lightning, XBility XB 1, AE RC28

WHEELBASE

• Only allowed wheelbases: 98mm and 102mm

MOTOR

• Any 1/28th scale manufacturer 3500Kv sensored motor
• Maximum can diameter: 15mm
• Maximum Kv: 3800
• No aftermarket rotors allowed
• Motors must not be tampered with or modified in any way

GEAR RATIO

• Any manufacturer pinion and spur allowed
• Tooth count must be distinguishable by markings or color for easy tech
• All gears must be Pre-Event teched and painted
• Standard ratio: 12T Pinion / 53T Spur (unless specified for track conditions by event)

WHEELS

• All brand plastic and aluminum 1/28 scale production wheels allowed
• Size specifications:
  • Front-wheel width: 8.5mm (not including outer flange/disk)
  • Rear-wheel width: 11mm (not including outer flange/disk)
  • Maximum wheel diameter: 20mm
  • Minimum wheel diameter: 19mm
• Wheels must be original designs made for 1/28 scale cars
• Wheel and tire must fit inside the body

TIRES

• Maximum tire diameter (mounted): 25.5mm
• Front tires must be 8.5mm and rear tires 11mm wide
• Tire warmers are allowed
• Tires may be cleaned with 70% alcohol solution or water
• Not Allowed:
  • Traction compound on tire or race surface
  • Homemade tires
  • Foam tires
  • Silicon tires
  • Urethane tires
  • Ethyl Carbamate tires
  • Tire inserts
• Using illegal tire cleaner will result in penalties

BATTERIES

• 2-cell LiPo or 2 one-cells paralleled (maximum 8.40 volts)
• Max battery dimensions 45 x 24.0 x 13.0mm
• Battery must be identifiable with original sticker from 1/28th MiniZ manufacturer
• Maximum 500 mAh
• An additional battery is allowed only for transponder connection

ESC / RECEIVER

• Any manufacturer 1/28 ESC and Receiver allowed
• ESC must not have any timing, turbo or boost activated and have a visual Blinking LED. (Blinky Mode)  
• Not Allowed:
  • Receivers with built-in Gyro
  • Separate Gyros

APPROVED LIPO 3500 BODIES

• PN: Supra A90, JSK, AD4, GT4LB, 992GT3, M4GT3, Concept C9, V2 JGT01, ZLB
• SBRC: Zenvo ST1, Phenom GT, NSX GT3, 458GT, SBX, STR, HYR, JX, XB2
• Marka: RK410, RK408, RK-S, RK-SP6, RK-HC, RK-P-One, RK-W, RK-12, RK-TWR, RK-4C, RK-AMGT, RK-BLD, RK-NTI, RK-PZR, RK-MK4, MK5
• Atomic: M4Z, DBX, Hyper, VST, ADR, IS2, LTC Type, LCT-2.0, AMZ
• GL Racing: P1M
• Rad Body: Mako GT, Mako X, Catfish
• PROTOform: P63, Venturi GT
• G-Force: VW
• RTRC: XVR-GTB
• Bitty Designs: Ares-1, Eptron
• Nexx Racing: NX-326 Body
• 102mm Wheelbase Specific:
  • GL Racing – P1M
  • Marka – RK-P-One
  • RTRC – XVR-GTB
• Wings:  Wings have 45mm height limit from ground

WEIGHT

• Full car minimum weight: 160 grams (race ready)

OPTION PARTS

• Any aftermarket 1/28 scale publicly available production or 3D printed parts allowed
• Adding weight via tungsten putty, stick weight, or cut hobby brass is allowed
• Not Allowed: Prototype parts
• Public availability requirements: Parts must be publicly announced via social media or website 45 days prior to race
• Parts must be available for purchase nationally 45 days prior to race
• 3D print files must be shared with the public 30 days before event start

This class debuted in 2025 is the newest addition to the 28SRA Grand Prix.

LIPO 2500 PAN CLASS REGULATIONS

CHASSIS

• Open any 2WD chassis ONLY
• Prototype or pre-production chassis allowed

WHEELBASE

• Only allowed wheelbases: 94mm, 98mm and 102mm

MOTOR

• Any manufacturer 2500 motor allowed (sensored or sensorless)
• 2800kv limit
• Maximum can diameter: 15mm

GEAR RATIO

• Open 

WHEELS

• All brand plastic and aluminum 1/28 scale production wheels allowed
• Size specifications:
  • Maximum front-wheel width: 11mm (not including outer flange/disk)
  • Maximum rear-wheel width: 14mm (not including outer flange/disk)
  • Maximum wheel diameter: 20.5mm
  • Minimum wheel diameter: 19mm
• Wheels must be original designs made for 1/28 scale cars
• Wheel and tire must fit inside the body

TIRES

• Front tires maximum width: 11mm
• Rear tires maximum width: 14mm
• Tire warmers are allowed
• Tires may be cleaned with 70% alcohol solution or water
• Not Allowed:
  • Traction compound on tire or race surface
  • Homemade tires
  • Foam tires
  • Silicon tires
  • Urethane tires
  • Ethyl Carbamate tires
  • Tire inserts
• Using illegal tire cleaner will result in penalties
  

BATTERIES

• 2-cell LiPo or 2 one-cells paralleled (maximum 8.40 volts)
• An additional battery is allowed only for transponder connection

ESC / RECEIVER

• Any manufacturer ESC (sensored or sensorless) and Receiver allowed.
  
• Not Allowed:
  • Receivers with built-in Gyro
  • Separate Gyros

APPROVED LEXAN & LMP CAR BODIES

• Cutting the rear panel is allowed
• PN: BMR, AMR2
• Marka: RK-AMR, RK-P99, RK-LM6, MRK-8031-07, MRK-8045, MRK-8046, MRK-8047
  
• Reflex LMP3
• Atomic: MP1
• SBRC: B001, B011
• Rad Body: LMP3 RAD001, Ocho, Skillet
• GL Racing – VDS
• GK Body GK-0001

OPTION PARTS

• Open any parts allowed (including homemade parts, 3D-printed, and prototype parts)

 

AWD MOD CLASS REGULATIONS

CHASSIS

• Allowed models: Kyosho Mini-Z Racer AWD MA010, MA015, MA020 and MA030, Atomic BZ and SZ2, GL Racing GLA, GLA Giulia, Mini-Q Q7, RTRC RTB

WHEELBASE

• Only allowed wheelbases: 98mm and 102mm

MOTOR

• Any manufacturer motor allowed (sensored or sensorless)
• Maximum can diameter: 16mm

GEAR RATIO

• Open

WHEELS

• All brand plastic and aluminum 1/28 scale production wheels allowed
• Size specifications:
  • Maximum front-wheel width: 11mm
  • Maximum rear-wheel width: 14mm (not including outer flange/disk)
  • Maximum wheel diameter: 20.5mm
  • Minimum wheel diameter: 19mm
• Wheels must be original designs made for 1/28 scale cars
• Wheel and tire must fit inside the body

TIRES

• Maximum tire diameter (mounted): 25.5mm
• Front tires max 11mm and rear tires max 14mm wide
• Tire warmers are allowed
• Tires may be cleaned with 70% alcohol solution or water
• Not Allowed:
  • Traction compound on tire or race surface
  • Homemade tires
  • Foam tires
  • Silicon tires
  • Urethane tires
  • Ethyl Carbamate tires
  • Tire inserts
• Using illegal tire cleaner will result in penalties

BATTERIES

• 2-cell LiPo or 2 one-cells paralleled (maximum 8.40 volts)
• An additional battery is allowed only for transponder connection
• ESC / RECEIVER
• Any manufacturer ESC (sensored or sensorless) and Receiver allowed
• Not Allowed:
  • Receivers with built-in Gyro
  • Separate Gyros

APPROVED AWD BODIES

• PN: Supra A90, JSK, AD4, GT4LB, 992GT3, M4GT3, Concept C9, V2 JGT01, ZLB
• SBRC: Zenvo ST1, Phenom GT, NSX GT3, 458GT, SBX, STR, HYR, JX, XB2
• Marka: RK410, RK408, RK-S, RK-SP6, RK-HC, RK-P-One, RK-W, RK-12, RK-TWR, RK-4C, RK-AMGT, RK-BLD, RK-NTI, RK-PZR, RK-MK4, MK5
• Atomic: M4Z, DBX, Hyper, VST, ADR, IS2, LTC Type, LCT-2.0, AMZ
• GL Racing: P1M
• Rad Body: Mako GT, Mako X, Catfish
• PROTOform: P63, Venturi GT
• G-Force: VW
• RTRC: XVR-GTB
• Bitty Designs: Ares-1, Eptron
• Nexx Racing: NX-326 Body
• 102mm Wheelbase Specific:
• GL Racing – P1M
• Marka – RK-P-One
• RTRC – XVR-GTB
• Wings:  Wings have 50mm height limit from ground

OPTION PARTS

• Any aftermarket 1/28 scale publicly available production or 3D printed parts allowed
• Adding weight via tungsten putty, stick weight, or cut hobby brass is allowed
• Not Allowed:
  • Prototype parts
• Public availability requirements:
• Parts must be publicly announced via social media or website
• Parts must be available for purchase nationally 45 days prior to race
• 3D print files must be shared with the public 30 days before event start

PAN OPEN CLASS REGULATIONS

CHASSIS

• Open -  any 1/28th scale 2WD chassis 
  
  • Production Chassis allowed
  • Prototype or pre-production chassis allowed

WHEELBASE

• Only allowed wheelbases: 94mm, 98mm and 102mm

MOTOR

• Any manufacturer motor allowed (sensored or sensorless)
• Maximum can diameter: 16mm

GEAR RATIO

• Open

WHEELS

• All brand plastic and aluminum 1/28 scale production wheels allowed
• Size specifications:
  • Maximum front-wheel width: 11mm
  • Maximum rear-wheel width: 14mm (not including outer flange/disk)
  • Maximum wheel diameter: 20.5mm
  • Minimum wheel diameter: 19mm
• Wheels must be original designs made for 1/28 scale cars
• Wheel and tire must fit inside the body

TIRES

• Front tires maximum width: 11mm
• Rear tires maximum width: 14mm
• Tire warmers are allowed
• Tires may be cleaned with 70% alcohol solution or water
• Not Allowed:
  • Traction compound on tire or race surface
  • Homemade tires
  • Foam tires
  • Silicon tires
  • Urethane tires
  • Ethyl Carbamate tires
  • Tire inserts
• Using illegal tire cleaner will result in penalties
  

BATTERIES

• 2-cell LiPo or 2 one-cells paralleled (maximum 8.40 volts)
• An additional battery is allowed only for transponder connection

ESC / RECEIVER

• Any manufacturer ESC (sensored or sensorless) and Receiver allowed
• Not Allowed:
  • Receivers with built-in Gyro
  • Separate Gyros

APPROVED LEXAN PAN CAR BODIES

• Cutting the rear panel is allowed
• PN: BMR, AMR2
• Marka: RK-AMR, RK-P99, RK-LM6, MRK-8031-07
• Atomic: MP1
• SBRC: B001, B011
• Rad Body: LMP3, Ocho, Skillet
• 102mm Wheelbase Specific:
• Atomic – MRZ
• GL Racing – VDS
• GK Body GK-0001

OPTION PARTS

• Open any parts allowed (including homemade parts, 3D-printed, and prototype parts)