hainz, they gave me 2 inch od pipe, which actually is 1.875 od pipe, only reason i say 2.5 is because of how much they crushed the pipe!!! the literally rduced the diameter of the pipe by 60% or more, they didnt follow the old exhaust route, they brough it down and up and down and up and all around crooked and shit.bigger pipe isnt always better, i understand there is a complex and in depth science about exhaust gases and the pulses the cylinders emit yada yada yada, although when i first installed my engine and ran it for a few days it was fun, i went and had this shitty exhaust put on and its like i switched from a fresh l20b with cam and dual carbs to an old ford tractor in need of a tune up!!! well maybe not that much of a difference but i know for a fact that this shitty bent exhaust really choked this thing down. on the top end i cant get it to wind up as fast, from 4 to 6000 rpm its much slower in winding up. when i had no exhaust it would wind up like a dog with his ass on fire and it would put your ear out doing it!!! i can really tell a difference with this exhaust and i threw a cherry bomb on it in an effort to offset the crushed pipe and i hate the soudn of it now, i need a good borla muffler or a high quality magna flow, i have tried the cherry bomb, and the thrush turbo and both of them sound awful, the turbo is alot better than the glasspack though. im gonna check on the status of the complaint today.