From what I've been told, and talking to most of the can manufactures I think Dyno Port out of New York has the best, They test all the cans and pipes on an actual dyno, they can tell you what works and what does not. They seem to be very knowledgable and helpful
I have a extra mbrp for sale it is new in the box. I ordered 1 and came across 1 before the back orderd 1 showed up. 279.00 plus shipping if anyone is interested.