its straight piped 2.5 inch into a y pipe into 2" duels, and i was goin to put the headers on and make it true duels

 

That would help. I would go with an H-pipe or X-Pipe, too. Basically it's true duals, but there is a section that links the two pipes to allow the pressure to even out between them and helps w/ evening flow.

I don't think I'd go more than 2.5in for the true duals.

Have you thought about high flow cats, or have you eliminated them already?