Simple performance mod : GET RID OF YOUR "SUPER TOURING 80,000 MILE " TIRES!
The car will only go as well as the tires can handle. Put some decent all-weather sport tires on and you'll notice a decent world of difference in handling and gain a small ( but largely unnoticeable) gain in acceleration. I have a 95 thunderbird that was a handling mess and then I put on some cheap sport tires (Dean Quasars, $70 apiece) and they've improved nearly every aspect of my cars handling. Your experience may vary. Some cars it will make a big difference for, some it wont.
The cons? Sport tires are expensive, wear out 20k miles sooner than regular tires, and are noisy.
If anyone says sport tires can be long lived, they are lying. There is no known way to have high performance and high life. Touring compounds are very hard and have less friction with the road, therefore they take longer to wear down. Softer sport compounds wear down faster but give better grip.
Disclaimer : Make sure you buy the right size, and don't go for DOT slicks or "supersport" tires. You do not want to run around in rain or snow with slick tires... traction is much worse than even the supertouring tires .
My edit :
For those who are about ready to jump all over me about calling the Deans sport tires.
The Dean Quasar series are not actually sport tires. But, they are 'sportier' tires than what I had on my car, simply because they have a better traction rating ( A instead of B ) and they have excellent foul weather performance (IMO). Yes, I have driven my RWD car in rain, snow and ice. Yes, I am stupid