FCVFD

I have a 98 with the 5.4 I want to run new exhaust pipe from the crossover pipe back should I use 3 or 4 inch pipe I'm looking for which would be loudest

jprevat

iTrader: (1)

If you run a 4" pipe you will be losing a fair amount lower end power. 3" would be deeper rather than louder than say 2.5 inch pipe.

TLB4

I ran 4" and I really enjoy it, but you have to make all your bends yourself and weld everything together, and kiddy corner some of the bends to make it work well. 3" would be easier, and you might be able to find a prefab'd complete pipe that you just bolt in place with a 2.5 - 3" reducer.
Overall, the 4" will have a deeper tone if that's what you're basing it off of.

You'll also need to weld on some supports and relocate a couple of them too because 3" / 4" will hit your shock .

FCVFD

Thanks for your help I'm not going the whole way back I just want to go behind the cab. I think I will go with 4 inch cause I have a buddy that has a machine to bend pipe and swell it