[pdupler]

Actually its closer to 2 7/8" but its hard to find that diameter anywhere. The problem with 3" is that the old rubber tends to split when you stretch them over. 2 3/4" exhaust pipe is available at muffler shops that do truck , rv and bus exhaust and works just fine. I did find some 2 7/8" OD pipe at a structural steel pipe supplier (like you might use to assemble a pole barn from) but it was just chance and they gave me a scrap piece but it was kinda rusty so I never used it.

Phil D

It's there for noise reduction. You won't gain any power but you will pick up a little extra noise. Unless I'm mistaken isn't the resonator 3 to 3 1/4" in diameter at the hose? I'm pretty sure its the same size as the AFM flange which you have to stretch a 3" hose coupler over.