exhausting the exhaust choices
I'm trying to choose the "right" exhaust for my E39 M5
A local tuner is recomending B&B.
From their web page it is difficult to determine much about their system on an E39 M5. Their specs all list a Dyno from a 1995 M3 and the photo is a E46 M3.
Also I notice these systems have 1 muffler for each side with 2 tips coming out. The stock system is 4 mufflers with 1 tip from each. Seems the stock would have better air flow? Or no? Also I have heard doing a X pipe is a good idea.
The other thing I'm looking to do at the same time as exhaust is doing the PowerChip. Gold probably. While I can find 93oct it's not available enough to rely on in my area. 91/92oct is everywhere. Any thoughts and opinions are most welcome!
Oh and for point of reference... my driving style is mostly summer time, weekends highway trips and BMW CCA/SCCA events 3-4 times a year.