what i am asking is will a twin setup breath through a 5" dp then necked down to a 4" y pipe dual stack setup? will it hurt anything, also will be running a 4" fte resonator.
got a 4" fte cheap, and my current y is 5". money is ging into twin setup for now. im sure ill get a 5" wye later, just not right now for the initial hook up.
I went from a (3" down pipe and 3.5" tailpipe) to (4" down pipe back) and noticed no fuel economy difference. It seems like the truck pulls harder, but the increased noise could be fooling my judgement.
I guess this doesn't really apply to your question. Oh well.
4" will be limited to a resonator and a foot of flex pipe to the 90 up into the bed and the wye to the 5" stacks. its a regular cab truck. i think im gonna be ok.