Now that I have a FULL exhaust on my otherwise basically stock 96, emissions compatable LT headers, 3" y pipe w/ dual 3" high flow cats, and a SLP Loudmouth catback, do I need to have the computer tuned to comply with such high flow? The oil pressure and everything looks good, but is there ENOUGH backpressure. Or does the computer adjust to the change on its own? I know I'm getting a HP gain, but would it be a better one with tuning, or should I just drive it until the computer adjusts on its own?

 

It will adjust on it's own fine, though you may want to get a tune because headers sometimes set off the knock sensor by sending "false knock"(it creates vibrations that the computer thinks is pinging) and not to mention they are dog-rich from the factory so you could probably gain another 10+hp depending on if the knock sensor is affected or not.

I've also heard that real low backpressure can cause the EGR valve to operate improperly, though it doesn't affect anything at WOT, it could kill your gas mileage.

 

The guy above made some very valid points. It appears we are both running similar exhausts. During my header install, I had trouble with the EGR functioning properly. I sent my PCM to madz28 and he did an emissions compliant EGR tune along with everything else. Long story short, my car passes OBD-II Illinois emissions with flying colors and that is with long tubes. Also, from what I have been told, long tubes lean out the cylinders a little so the tune basically adjusts the A/F mixture to compensate. Also, the tuner can "desensitize" the knock module which is a very good thing when it comes to the addition of headers. For the 125.00 it will cost you to have a mail-order tune done, it is well worth it. I could right a two-page post about how happy I am with mine.

 

With MADZ28, do you just remove your computer, and ship it to him? So youre computerless for a little while? I'm in storage, no matter, but still.?

 

He will send you a tuned PCM and you send him your old one eliminating any downtime of your car.

 

oooohh. . . so there's no need to have your origional computer?

 

He takes your old computer as a "core" and reprograms it for the next customer. You could keep your old PCM and receive his programmed PCM as well, but it will cost you an extra 140.00 I believe.