Originally Posted by DusterKid
I'm going to be building my own set of fenderwell headers with 1 7/8 primary tubes should I use a 3 or 3 1/2" collector? Race only engine, Big block 440 see's 6500 rpm max, est 525-550 engine HP.

Respectfully, I wouldn't build fenderwell headers until you NEED to poke them out the fender. e.g.- OVER 1000HP Plenty of room to accommodate 2" or larger in a b eng a-body and do it clean and 'correct'. Also, if you're building custom just use 2" x 3.5" IMO OR BUY the TTI. While I dont like them, they seem to work pretty OK!