The real question is what size are the twin pipes coming out of the cats? Or is that one of them? That makes a HUGE difference. That would make the outlet cross section 6.283 sq. in. total , not 3.543
Quotes to live by:
guessing gets expensive
nothing is more expensive than a cheap BMW
Ken Kanne, Silverhill, AL, Honorary Forum Grandpa/Craigslist addict/Hoarder of all sorts of stuff
1995 318is "Bebe"; 1993 325is "Elvira" 1985 635CSi "Katja" 1984 633CSi "Sylvia"
I NEED A NAP, DANG IT!
Last edited by hornhospital; 02-15-2013 at 04:22 PM.