Mac all the way. I had flows with bbk h-pipe and bbk longtubes. I now have full mac and pro chamber pipe. Sounds awsome. I changes the cat back first with the old setup and it already sounded much better.
One more question, how does the weight of the MAC system compare to stock ?? It seems like it might add weight with all of the additional connection points... does anyone know ?
I am running Mac LT's and ProChamber with 2-1/2" straight pipes out the back. Sounds mean as hell and is as loud as it too. Strangly fairly quiet inside too. Kinda weird.
I originally had MAC on my 5.0. It sounded good but fit like ass. I used to have to go under it every couple months and readjust because it would work loose from hitting the axle or control arm or something.
Eventually i noticed it was hitting a brake line and almost broke it. I finally threw it in the trash and bought a flowmaster 2-chamber cat-back setup. The fit was 100X better than MAC.