Anyone know the diameter of the collector on the stock manifold? Looking to pick up a shorty header from CA off the classifieds and was told the collector is a 2 inch. I already upgraded to a 2.5 Zzp down pipe and corsa catback. I just don't want to make this thing slower than it already is.

 

id say your good smooth flow from 2inch to 2.5inch if it was 3inch to 2.5inch i would say u lose hp flow makes a big difference ie. badmab there only good for s/c with full 3inch exhaust

 

i have a badmab. i love it