m5board.comoholic (>1000 posts)
Join Date: Feb 2007
Location: Atlanta, GA
Thanked 316 Times in 215 Posts
In actuality the removal of the primary cats (built into the stock headers) is what truly makes the hp gains. The RPI product IMO proves this.
Exactly. Wishful thinking, but I'd love to see some dyno numbers on stock headers without the primary cats.
2006 M5--Sapphire black/sepang
Dinan: free flow exhaust, Stage 3 engine software, high flow throttle bodies, high flow air mass meter/intake Assemblies, stage 2 suspension, 13% underdrive crankshaft pulley, 5.8 liter stroker engine, Dinan middle exhaust section, custom headers (I think I am finally done)
2011 Space Gray ZCP E92 M3; two-toned black and red interior; Dinan 4.6 liter stroker engine, intake, exhaust, midsection, pulley, and throttle bodies.