does anyone know how a true echaust from headers with 2 1/2 inch exhaust with no cats would sound or if this is a real bad idea with no back pressure at all?

 

Never heard it before. But I can tell you this much, you will NOT want to use 2 1/2" for the system. 2 1/4" is the biggest I would go. Good rule of thumb when doing real dual exhaust is to never go bigger than stock exhaust size after the header collector. Also, I advise using a H-pipe in your dual set up after the headers if you go this route.

 

no back pressure = no power i agree with phil that if your gonna go with dual exhaust it needs to be tied together. besides a single piped exhaust can sound just as good as a dual.sometimes better depending on motor displacement and the flow through cats and muffler or mufflers.