exhaust pipe sizing for combining/splitting

[just a number]

I need to reroute the exhaust setup on the truck. getting tired of the rattle of the pipe hitting the cab/firewall or where it goes over the frame. I was thinking of splitting it right after the turbo and running something about 2.5" duals?

I can't seem to find any real useful info on it. everybody assumes you running a hi performance gasser.

know any good websites or formulas?

 

[Jorge6.5]

The turbo is the restriction so after that you can go as big as you want. Complete diamond eye turbo back 4in. for $260 shipped

 

[jrsavoie]

Go with stainless for the exhaust. I've had aluminized start to rot in 3 years.

 

[just a number]

it the truck in my sig. right now it has a 3" running down between the passenger inner fender and the cab/firewall. the problem with that is that it rattles against the body. there's not quite enough room to run the 3" where the gm 400's(88-98) run theirs.