Simple question. I'm sure it has been asked many times on here before. I'm like most people. I have a 2000 C5 6sp manual coupe and I have done an intake, long tube headers (w/cats) and a Corsa X-Treme axle back muffler system. Now I get the pesky check engine light (P0420) from the rear O2 sensors. Most of the tuners around here (Toledo OH) do only imports (sadly) and don't know the GM product.

Sounds like a result of the high flow cats, I had the same issue when I installed my LT headers and high flow cats, the only way I know of to resolve it is to have a tuner turn off that check in the PCM. That worked for me. otherwise its not an issue that will impact any performance.

If you do a Google search for "tuning" , you should find lots of books, onsite courses and online courses designed for the beginner. Good luck! :thumbsup3:

Thanks guys for posting a response. This thread sat dead for awhile. When I logged on today, Smokinvette had a very informative article on the left side of the page that dealt with the topic of tuning and how to learn more about it. They sited three websites: www.thetuningschool.com www.calibratedsuccess.com
www.masterenginetuner.com

They also posted an E-Mail resource:
Tunerlocator@cfl.rr.com You can E-Mail them with your make/model and list of mods and they will refer you to a tuner in your area. haven't actually pursued this just yet due to other time constraints but I will be doing so soon. Thanks again!:burnout:

I purchased the HPTuners pro, but it wasn't much more than a paper weight until I took the tuning school, (where I got to dyno tune my own car and picked up over 100hp over a tuners work)
Now I have a decent understanding of the process, and can tune all of my cars, although Im a LONG way from being an expert :thumbsup3: