I installed LSD test pipes and a Borla exhaust system Tuesday morning, everything was fine until Thursday morning, I gat the dreaded "Service Engine Soon" light. I've done a search and it seems that most people wait this out and it goes away. My question is does the light affect anything besides my annoyance threshold? Does it "dumb down" the car?

 

Should be fine. The O/2 sensors got freaked out with all the air flow. If you have a friendly dealer around (like us) they should be able to hook up their consult unit and shut off the light in a few min's. I would hope they wouldn't charge you for that.

 

I'm not sure if this works on our nissans, but it does on almost every other obd car. Disconnect your negative battery terminal for 12-15 minutes and then reconnect it and start your car. Just let it idle don't give it gas or anything. Let it idle for about the same time (12-15). That should clear your ecu and let it re-learn everything.