Need a 3 1/2" to 3" Cold Air Adaptor

I purchase intercooler adapter hoses from Forced Performance.

I am willing to bet Cotton's performance can hook you up as well.
Lowes, Home depot, Menards or other hardware stores with plumbing supplies.

Fernco makes a 3in to 3in sewer pipe adapter that is black rubber and includes clamps It fits over the 3.5 LS1 Maf and compresses easily to fit a 3 inch Maf pipe. I got mine at Menards for under $4.00. Bob Bailey is one of the people that suggested them.

fullthrottleperformance has them listed on their website.

Usually they stock that sort of stuff.