LS exhaust suggestions

[glassman]

Hey all, so my LS conversion hit a bump in the road. Everything was kinda dialed till i put my new/old exhaust system. New meaning it was installed behind my sbc in April of last year, 2.5 pipes and Magnaflow with turndowns. So we cut it and welded on the Dynatech header adapters then the car ran like sh!$. My tech/friend thought it was in my head, and he said drive it uncorked, we'll we did. Huge differrence. He measured the backpressure with a guage through one the of O2 sensor holes and it came up with 7, he said anything above (?) was too much and we're like double that.

What type of crosspipe recomendation?
We were told a need of some backpressure is required, so we went 2.5.

Runs good now, uncorked, but i cant leave it like that....or can i (hehehe)? JK

So suggestions for a kickass exhaust?