Deadline for comments is
March 1st


ME1 Mid-Engine Class – DRAFT

Upated as of 10/18/2023

ME1 Class Rules and Eligible Models

This is a multiple-model BOP class that consists of second-generation 986 base 2.7L Boxsters (00-04) and first-generation 987.1 base 2.7L Boxsters (05-08) and Caymans (07-08).

Questions?  Use the “Comment” pop-out or send to

1. Engine

Base 2.7L 986 Boxsters must use the M96.22 engine (00-02) or M96.23 engine (03-04). Base 2.7L 987.1 Boxsters must use the M96.25 engine (05-06) or M97.20 engine (07-08). Base 2.7L 987.1 Caymans must use the M97.20 engine.

  1. General. The mechanical and electrical components of the engine and transmission must remain stock and in their stock locations.
  2. Cooling System. Must remain stock with the following exceptions: The left and right stock radiators may be replaced with high efficiency front radiators provided they fit into the stock mounting points. Shrouding around the left and right radiators may be modified to allow for more efficient air flow to the radiators. A center radiator may be added and can be either a Tiptronic , GT3 or high efficiency type. The center radiator may only be vented out the bottom. Radiator fans may be direct wired with a switch, and one or both of them may be removed.
  3. Oiling System. The factory oil and oil cooling system must remain stock, except an external oil cooler, an X-51 oil plate, an aftermarket sump extension or sump pan, a Porsche Motorsport or aftermarket Motorsport oil/air separator (AOS), and an oil accumulator (e.g., Accusump) may be added.
  4. Power Steering Cooling. Power steering fluid cooling is free.
  5. The engine driven power steering may be switched to an electro-hydraulic power steering system as long as the hoses mate up to an otherwise unaltered stock rack.
  6. Air Filter and Intake. No modifications to the factory engine air inlet or intake system. Drop in factory size/style replacement air filter elements are allowed. Non-stock cold air intake enhancements are not allowed.
  7. Pulley/Belt System. An under-drive crank pulley is allowed, with a minimum 4″ diameter. No modification is allowed to: water pump or alternator. The air conditioning pump may be disabled or removed. All must be operable, and belt driven, but belt length is free. For electro-hydraulic power steering systems, a dead pulley may replace the power steering pump pulley.
  8. Fuel and exhaust emissions control systems may be removed, blocked, or modified so long as no performance advantage (other than less weight) may be achieved in so doing.
  9. Semi-solid engine mounts are allowed.
  10. The engine air injection system may be removed.
  11. All cars can use aftermarket headers from any manufacturer. Exhaust behind the header collectors is free. The exhaust system may be externally wrapped or coated.
  12. 986 base Boxsters can Flash their ECU. The Flash tune for 00-04 Boxsters is Softronics Software Part No. SFT-ME1-0004. No other ECU Flash tunes are allowed. All other models must use a factory stock ECU Flash. The stock base ROW Flash is allowed for all models.

2. Body/Chassis/Interior

  1. Rules applicable to 986 and 987.1 Boxsters
    1. Soft convertible tops and motors/assemblies may be removed. The clamshell piece over removed components may be attached to the body in any secure manner.
    2. Hard tops are mandatory and may be factory or aftermarket fiberglass replicas. Rear window must appear stock with no venting, can be Lexan.
    3. Approved air dams and bumper covers are limited to the following, including replicas:
      • 986 stock or stock with cutout for additional radiator
      • 986 Boxster S
      • 996 Carrera 2 (U.S. delivered 1999 C2 model)
    4. Arm restraints are required for drivers of cars with aftermarket hardtops, except as specified in CR Section 5 – Driver Requirements of the PCA CLUB RACING SAFETY section of this document.
  2. Rules applicable to all cars
    1. Air dams and bumper covers must be stock unless otherwise specified above. The front bumper must be located in the factory position and cannot be moved in any way. The fog lights and their support structures may be removed.
    2. Splitters – GT3 style factory PN 996-505-986-91, GT-Racing PN 661S or exact replica only. Splitters may not extend forward of the front bumper cover and may be no more than 3” lower than the bottom of the front bumper cover. Factory or factory replacement side skirts are allowed.
    3. Headlights, tail lights and brake lights must remain stock; license plates, frames, and license plate frames may be removed. Rear bumper cover, license plate area may be cut out to 27” wide by 7” tall maximum. Tow hook hole maximum 6” x 3”. The rear metal bumper may be removed, and a steel reinforcement added in its place..
    4. Rear spoiler may be stock, 987 Cayman R or exact equivalent (such as the GT Racing Porsche Cayman Aero Style Wing/Cayman R -Wing) for all Boxsters and Caymans. The stock spoiler can be permanently affixed for Boxsters. The 987 Cayman R wing should be permanently affixed on either Boxsters or Caymans.
    5. Radiator inlet screens, right rear fender side inlet scoops and screens, and ventilation inlet ducts are allowed. One or both side radiator fans may be removed.
    6. The windshield may be replaced with polycarbonate (Lexan) of suitable thickness. The door windows may be removed. Quarter windows may be replaced with polycarbonate and vented to direct air in or out of the cockpit but not into the engine compartment. If hood pins are installed, stock hood latches may be removed or disabled.
    7. The windshield wiper arms and blades and the windshield washer tank and washer mechanisms may be removed.
    8. All cars must display four approved TOYO decals, one on the front, one on the rear, and one on each side.
    9. Electrical wiring for parts which may be removed may be removed.
    10. Seam sealer, undercoating, weather stripping, and tubing for water drainage may be removed.
    11. The plastic fender liners may be removed, or holes cut in them.
    12. Thermal insulation and shielding may be removed.
    13. Grills to prevent entry of debris are allowed over all exterior openings.
    14. There must be a stock exterior mirror on each side, and an interior mirror. The interior mirror is free.
    15. A dry break port which complies with the Safety Recommendations and Allowances at the front of this rule book is allowed.
    16. The horn may be removed.
  3. Chassis
    1. Seam welding of the chassis is not allowed.
    2. Roll cage members may not extend through a firewall,
    3. Bolt-on tiedowns may be added.
    4. Air jacks are allowed.
    5. A fuel cell is allowed.
    6. Battery minimum weight is 10lbs; must be in stock location.
    7. All roll cages must comply with Appendix A. All Boxsters must have a minimum of 6 connection points to the chassis.  Attaching to the windshield frame or B pillar is allowed.  Boxsters may remove factory rollover protection bars behind the drivers seat.  Boxsters (but not Caymans) are allowed, but not required, to pass roll cages through the bulkhead and attach them to the front shock tower.
    8. Ballast may not exceed 100 lbs.
  4. Interior
    1. A passenger seat is allowed but not required.
    2. The factory dashboard instrument pod must remain intact. Additional gauges may be added. Factory navigation systems, radios, entertainment systems, and airbags may be removed. The lower portion of the dashboard may be removed.
    3. Steering wheels are free. Quick release steering hubs are allowed.
    4. The steering wheel lock must be disabled or removed.
    5. The air conditioning/heating system (including, without limitation, the heater core and its containing sheet metal) may be removed or disabled.
    6. All interior items may be removed except where otherwise noted. All carpeting, trim, insulating or sound deadening material, and non-metal panels may be removed from the interior.
    7. Doors may have window, lock, and interior latch mechanisms, and any other pieces held on with fasteners removed, but must retain all of the metal perimeter frame, hinges, and door latch mechanism. The interior latch may be modified but must work. Factory door beams must remain intact unless two cage door bars are installed for that door. If NASCAR style door bars are installed, the door perimeter frame may be modified, but only as much as is needed to fit the door bars.
    8. Shift knobs are free.
    9. The immobilizer box may be relocated inside the driver’s compartment.
    10. The driver’s footwell fuse panel may be relocated inside the driver’s compartment.
    11. Factory engine cover must remain in the stock position and latched.
    12. Data Acquisition and in-car timing equipment is allowed.
    13. For 986 Boxsters, 996 instrument clusters are allowed.

3. Brakes

  1. Brake pads are free. Insulating and heat dissipating backing plates are allowed.
  2. Steel braided brake lines are allowed.
  3. 996 or 997 GT3 master cylinders are allowed.
  4. Brake dust guards may be removed. Ducts, scoops, deflectors, vanes, block-off plates, and other systems within the bodywork to direct cooling air to the brake rotors are allowed.
  5. Brake cooling systems are allowed, provided they use only air. The fog lights may be removed, and the openings used for brake cooling, but additional exterior bodywork openings are not allowed. Modifications to existing air channels inside the bodywork to duct air for brake cooling are allowed.
  6. One-piece rotors must be used and must be dimensionally the same as stock. Drilled and slotted rotors are allowed. No component of the ceramic brake option which is different than the base model brake system may be used.
  7. Brake calipers must remain completely stock and mount in the factory location. Stock-sized stainless steel pistons may replace the stock aluminum pistons.
  8. The emergency brake, lever, cables, and all associated parts may be removed.
  9. The ABS may be re-Flashed (as noted in the overall safety provisions) for 987.1 cars to run in PCCB mode to prevent ice pedal.

4. Suspension

  1. All suspension components not otherwise listed must be stock factory parts. Stock suspension parts may be used in lieu of permitted other parts for all cars. All suspension components must be mounted in the unmodified factory original mounting locations. Except where specifically noted or a part is listed as free, no solid bushings are allowed.
  2. Shock Tower Braces. The welded-in cage may be connected longitudinally to the tops of the rear shock towers. No other modification of any shock tower is allowed nor are strut braces permitted.
  3. Rear Subframe. A bolt-on cross tie bar connecting the rear suspension subframe sides is allowed.
  4. Front and rear two-piece lower control arms are allowed. The must be Porsche Factory shim adjustable front outer control arms for the 996 GT3 or 997 GT3, or a replica aftermarket replacement under the CR Suspension Section 2.S for Stock Cars. The inner control arm bushing and the caster adjustment inserts, which secure the radius arm, for the front lower control arms, must remain stock (rubber). Radius rod (thrust arm) rubber mounts for the rear suspension must remain stock.
  5. Front radius rods (thrust arms) must be stock 986, 987, or street 996 parts. Spacers may be used to adapt stock radius rods for use with the specified 996 control arms.
  6. The rear toe (track bar) links are free and may include bump steer adjustment.
  7. Aftermarket locking plates may be used on all suspension adjustment eccentrics.
  8. Springs, shocks and monoball topmounts.
    1. All cars must use the Tarett ME1COP coilover assembly. Any combination of 600 or 650 lb/in springs are allowed either front or rear.
    2. All spring and shock systems must mount in the factory original locations.
    3. The upper shock mount sheet metal may be cut to allow full use of the factory adjustment slots if shock adjusters protrude enough to hit the metal, but only enough as is needed for the adjustment purpose.
  9. Front sway bars must be 29mm or less in diameter and mount in the stock front sway bar position, but are otherwise free. Rear sway bars must be 20mm or less in diameter and mount in the stock rear sway bar position, but are otherwise free.  Cars are allowed, but not required to run rear sway bars.
  10. Sway bar drop links are free.
  11. Any ride height is allowed, as long as no part of the vehicle other than the tire patch touches the pavement.
  12. The stability management system may be altered by disconnecting or switching sensors.

5. Transmission

  1. Allowable transmissions are as follows: 986 2.7L Boxsters must use either the G86.01 5 speed or G86.20 6 speed transmission. The 987.1 Caymans and Boxsters must use either the 5 speed G87.01 or G87.20 6 speed transmission.
  2. Transmissions must be stock with no modifications. All gear ratios must remain stock. Ring and pinion ratio must remain stock. Aftermarket gears that are the same as stock ratios are allowed for the G86.01 or G87.01 transmissions. No straight cut gears are allowed as replacements.
  3. A separate pump, cooler, and fittings for transmission cooling is allowed.
  4. Clutch assembly and fly wheel may be factory stock, or be replaced with the Factory replacement or Sachs 88-3082-999-754 clutch, Sachs clutch disc 88-1861-000-017 kits and lightened flywheel Aasco PN 106412-11, Fidanza 914572 or Clutch Masters FW-005-AL.
  5. A mechanical limited slip differential (LSD) is allowed.
  6. Factory compatible short shift kits, shift risers, and alternate cables are allowed, but other modifications to the shifting action (e.g., sequential, paddle, blippers) are not allowed.
  7. Semi-solid transmission mounts are allowed.

6. Tires/Wheels

  1. Any single piece aluminum rims intended for the 986 Boxster or for the 987.1 Boxster or Cayman are allowed that match the original offset; front wheels must be at least 18.5 lbs. and rear wheels at least 20 lbs. Rear wheels must be 17 x 8.5-inch , 48-50 mm offset. Front wheels may be either 17 x 7-inch, 55 mm offset, or the same size and offset as the rear wheels.
  2. Wheel spacers are allowed only for 17×8.5-inch front wheels for fender and fenderwell clearance. A 1/4-inch spacer for the rear wheels is allowed.
  3. Tires: Toyo RR front 235/40-17 or 255/40-17; rear 255/40-17. Any DOT tire with a tread wear rating (UTQG) of 100 or greater can be used as a rain tire.
  4. Hubs may use studs in place of wheel bolts.

7. Weight

(will be added to Weight Chart)

00-04 Boxster w/ 5spd or 6spd transmission– 2750lbs/w driver.
05-06 Boxster w/ 5spd or 6spd transmission – 2800lbs/w driver.
987.1 Caymans and Boxsters w/5spd or 6spd transmission – 2850lbs/w driver.