Wondering.... Will the rear O2 cause performance issues....
I've been throwing the code for a while now.... since I've had the header and Carsound highflow cat put in...
I know that the cat isn't the one that should have gone in... looks to be too short...
I've been hearing that the header retains some of the heat and melts some of the catalyst.
Any light on the subject would be great
what type of codes are you throwin? ? shortly after my header catback exhuast was installed i was always throwin codes p0420 and p0133
its could also be your high flow cat. I dont know where you got it (never heard of it), but if it was one of the cheapo ebay ones that could be the start of your problem. Most of theose ebay high flow cats and toast in a month or two.

"Custom cars, custom problems."-me
Carsound makes the highflow cats for magnaflow...
as for the code.... it's P0420 Catalyst System Efficiency Below Threshold
i used to just keep erasing codes 420 and 133 but eventually i replaced the front o2 sensor and put in an o2 simulator for the rear . now its rare that 420 comes up and i havent had code 133 since then. u can make an o2 sim or buy one from casper electronics.
scrawnyguy18 wrote:Check out this post You can make a simulator for really cheap and some people have had success with eliminating the same code that you have.
This mod works! I put a hole thorugh my converter. Which was fine for about 15k miles. Then it started throwing the code. I would reset but after about 10 miles it would come back on.
Did this mod and still no code yet.