i've read a lot of threads especially dealing with the ypipe install in which everyone says reset the ecu after you install the pipe so it can get the settings right. what kind of settings would the ecu store that deals with how big the exhaust pipes are? and if there are these settings why wouldn't the ecu just automatically adjust when it runs for the first time with the new pipe?

 

Well, from my experience, sometimes it DOES reset itself. Other times, you have to "coax" it a bit. Hence, the reason for resetting the ECU...

As for what codes the ECU stores in relation to the exhaust, I believe they are O2, EGR, a lot of your temperature sensors, and some other stuff. I don't profess to know much about the codes and such, so a lot of what I'm rambling off is off the top of my head.

 

Some ECUs learn the way you drive and pattern the outputs accordingly.
and any time a mod is made that changes power output the ECU has to relearn because the outputs have to be change to get the pattern correct again.
A former boss of mine ad a 96 or so dodge ram p/u.
He bought a K&N procharger kit and put it on, without resetting the ECU. He didn't notice any power increase.
So then he read the instructions and they said to reset the ECU which he did (after asking me why)
He said the difference on the butt dyno was massive.
of course it still wasn't much faster than the SE-r