i have a question that needs to be answered. B18c, w/crower stage 2 cams , retainer & spring kit, 11.0/1 C/R, ported head & intake manifold, skunk2 cam gears, 4-2-1 header, ported t/b, hks filter. my header outlet is 2 1/4". i need to know if 2 1/2" is necessary for my project? i do know that most of the aftermarket exhaust systems use 2 3/8" or 60mm piping. well, the internal diameter of 2 1/2" piping is, you guessed it, 2 3/8". my question is has anybody done any type of dyno testing with this type of motor and and the aformentioned piping? i have seen turbo SRV’s with 2 1/2" piping, is it necessary for this much smaller N/A motor, because everyone goes 2 1/2" for the top-end, but i’m sure, they sacrafice tonnes of bottom end torque for a burst at 8000rpm. give me your input.(my rev limit is 8900rpm) thanks