Yeah, I've read a ton about HP gain etc - it seems the way to go is a tune/intercooler/DP.
Did you just cut the rear muffler out of your stock exhaust? I'm getting a shop to fabricate some quad tips as I've just upgraded my diffuser... is it worth asking them to chop the muffler out while they're at it?
no issues with backend pressure or anything
as I only want to upgrade the exhaust for the noise, its much too quiet for myself as I'm coming from a big V8 with a 3" exhaust.