Originally Posted by askiles
Why is your graph cut off down at around 3k RPM's, and does not show any lower? I had mine dynoed today, and there is a big dip at about 2.5k. Did this happen to yours? The guys are assuming it was due to such a great flowing system, that the enginer leans way out (and it did), and take a second to compensate. This was verified by looking at the AFR's. Anyways, let me know if yours did the same thing. Thanks!
Fact is when you do down pipes of any nature, you really need to get an ECU remap designed specifically for down pipes (e.g. Powerchip Stage II).
I'd suggest the engine is still running closed loop fuelling around 2500RPM and ECU is not dealing with the changes in O2 sensor readings very well (since there are no longer any cats in front of the O2 sensors).