I am going to be redoing my exhaust from the heads back in the spring. My plan is to run JBA headers (1 5/8" primaries), down to 2" pipe, high flow cat on each, then into an x-pipe and then run straight back to where they currently dump. My questions is: with ported alabama heads, how small does the pipe need to be to provide adequate back pressure to keep my bottom end torque? is 2" too small or can I run 2 1/2" and still be okay? I already have around 40' of 2 1/2" laying around the shop.
2000 XLT 4x4, 4dr ext cab, 4.0L OHV, 4.10 LSD
265/75/16 Goodyear Duratracs
Mountaineer seats, Expo OHC
2003 EDGE front clip conversion
1969 Mercury Cougar
351W, FMX, 3:1 open diff in a Ford 9"