Yeah that is nice site. I have been messing for regeisty for years. It doesn't really give huge perfomance boost. The most benfit I got was 5% gain and that took about 2 hrs to tweak. If you want faster machine you most overclock. If you do overclock do it slowly. And test test test. Right now out of my old amd 1800xp got extra 500 mhz out of. If you going to overclcok make sure have I good heat sink and other fans to keep her cool. If raise the voltage your machine will ran hotter and heat is the enemy.
2007 Dodge Caliber v4 5714 miles(cvt) tranny)
2002 Malibu 3100 117000 miles