I have a 97' Regal GS Supercharged, best car ever owned by me. I would like to do a few things but I definately need some advice on what quality products to buy. I would like to put a better exhaust system on it, hopefully without spoiling the 25mpg average i get. I would also like advice on other things to improve performance without sacrificing efficiency. I know for sure that in the spring I will be tinting the windows but i dont want them limo dark. I would also like to put nice rims on it, mine are beat up a bit, but thats age. I would also like to put a nav system in it, I've looked at Eclipse and Pioneer but don't know what is best for my money. Any advice would be greatly appreciated.

Welcome to AF.

On exhaust mods I would consider a hi-flow CAT convertor and get rid of the U-bend (delete) which is located after the CAT but before the resonator. If you over mod exhaust you may lose fuel economy. If you are looking for sound I would forget it. It doesn't make any difference if you use Flowmaster, Borla, etc. it doesn't sound right. Too ricey to me.

what would the high flow cat converter do for me?

The stock GM CAT is restrictive. The hi-flow CAT wll reduce backpressure within acceptable limits and in conjunction with the u-bend delete give a horsepower increase although it is marginal. It is a standard mod that Regal GS owners do.

Of course there are alot of other mods than can be done but most will affect fuel economy. Most common is a smaller supercharger pulley like a 3.4" versus the stock 3.8". It will give a few more psi of boost.

for future reference what are some other common mods? just incase