There are no ECU upgrades...they simply are not available. (don't believe those EBAY chip ads)
You can get a larger throttle body, but I don't think it would help unless you had a plenum/intake matched to it.
Headers are iffy at this point (only one company, 3sx, makes them, no Dyno results yet). They look nice (well made) though, and the will be an improvement over the stock exhaust.
The dealer or a junkyard would be your best bet for changing the plastic panels/lights, etc...I prefer the stock look myself, but to each his own.
I know a little bit...but most of my knowledge has come from being an owner for the last 6 years...
There is a running joke I've seen....The 3/S, making mechanics out of regular people since 1991.
