Class A - For cars and engines/ECUs built and raced between 1st January 1996 and 31st December 2004, with a 26mm engine air restrictor. Class B - For cars and engines/ECUs built and raced between 1st January 1992 and 31st December 1995, with an engine air restrictor of up to 26mm.

Masters Class - For cars and any engines/ECUs built and raced between 1st January 1985 and 31st December 1991, with an engine air restrictor of up to 25mm.

Note: A Masters Class driver may, upon entry to the Series, elect to run their car in either Masters Class with a 25mm air restrictor, or in Class B with a 26mm restrictor upon an existing Master Class engine. In addition, when electing to compete in Class B, engines/ECUs built and raced during the defined time period (as above) for Class B cars can also be used with a 26mm air restrictor. (In all other respects Master Class rules apply).