Originally Posted by Malekreza11
There is a pretty substantial difference in total power and torque gain, and how the power is gained within the powerband.
The factory unit is not a true x-pipe by any means. I have cut the factory x-pipe apart to see what BMW did inside of their so called "X" and it is a joke. The internal merge is roughly 1.1" in diameter.
The secondary cats to help the smell a little bit.
Power wise as a test, I have run a full catless modified OEM unit, and the gains were very marginal at its best. Power delivery was erratic because exhaust design requires engineering and tuning to compliment the powerplant.
Deleting cats does free up some power, but that is not where all the power lies.
Hmm interesting. What are your thoughts on systems that don't throw CELS? do they actually gain solid power? Because honestly I don't want to mess with software quite yet.