I had Kinetix cats for a while. They were great and a nice lower price alternatve to the Crawfords.

 

I've heard that right after an ECU reset the car runs way rich. I can't imagine that happens in a couple days tho...

 

Actually, I've read in the link that I posted that running lean is far more dangerous to a cat than running rich. The lean condition causes high exhaust gas temps which fatigue the cat elements.

With that said, with today's ECUs and emissions control systems, you're not going to run dangerously lean or rich. Sure, mods may throw your A/F to upper ends of the OEM ECU limitations, but it's not going to blow your motor or burn out a cat. The O2 sensors and knock sensors will keep that from happening...at least on an NA car.

 

Yep, right after a reset, the car will run rich hence the reason the car feels boggy after a reset and why the intake noise is soft. Over the next 30 to 40 starts, the ECU will slowly dial in the right overall A/F. The default rich A/F is there to save the motor when the car is first run to compensate for atmospheric conditions.

 

Only thing that makes me wonder is why when I had the stainless Injen on my car after a reset, my car sounded like a cobra - massive noise that disappeared after a few days of calming the ECU down. I gave up trying to figure it out and just do a reset for the TCU to tighten up the shifts and stop slipping/pausing on the 2-3 shift when at 1/2 or 3/4 throttle. The car can feel like a bucking bronco...and not because of what you're thinking.