I did a quick search but didn't come up with any exact info...

I know the stock size piping is 2 1/2" is this OD or ID? I ordered a dynomax race bullet from napa yesterday and it is also a 2 1/2" SI/SO...basically will these just butt up and i'm going to have to put a coupler around both of them?? or will one slide in the other one??

also on the bullets, was i wrong to go with the shorter length one?? i think i got the 12" instead of the 18"...I knew in magnaflows the 18" resonator was just a tad louder than stock so i went with the shorter bullet, thanx