lollercoaster... I finally discover the importance of tire pressure.
 

I finally got around to checking my tire pressure AFTER the tires were hot (with my new Longacre gauge), and after dropping the pressure (which went up about 5 PSI), it handled like a totally different car... much more grip and less tendency to over/understeer.

then again I was still slow as fudge.

Ah well...

On street tires?

Similar experience here. I finally got the hang of adjusting tire pressure to correct for over/understeer.

Yes, if I had race tires I wouldn't be nearly as slow...

As an amateur, I just set my tire pressures after a hot lap and leave it as is as long as the tire wear looks right I'm golden. There are other things I need to worry about other than my tire and suspension setup. :)

Next you need to get a pyrometer, by measuring the tire temp at the edges and middle of the tire, you can figure out whether you are using the entire surface of the tire to the full extend. It will help you figure out what tire pressure to run (it won't be perfect, but get you in the ballpark).