Mazda Motorsports restrictor plates for SCCA and NASA SpecMiata competition. Available in 38mm (0000-06-5239-99) and 40mm (0000-06-5240-01) sizes per the rules.
From the SCCA GCR page 557 section 9.1.7.J.1.d
"1.8L cars must use an air restrictor plate. The restrictor plate must be placed between the throttle body and plenum. All intake air must pass through the restrictor plate. Restrictor plates must be the proper size as listed in the specification table, must be from Mazdaspeed Motorsports Development or from SCCA Enterprises, and must not be modified. An OE (or equivalent) gasket shall be used on both sides of the restrictor plate."
Refer to GCR page 566 for official listing of size of restrictor plate for your year of car.
We have listed the legal restrictor plate sizes per model year for your convenience. It is the competitors responsibility to validate the numbers for their model year car via the GCR.
1999-2000 = 38mm
2001-2005 = 40mm
Price is for Qty (1) restrictor plate.