Another Newbie

Hey Guys Newbie here name is Birge. I have just aquired a 1995 Monte Carlo LS,3.1 Liter. Shes got about 124000 miles but still whips the head back pretty good wehn you mash the pedal. I have a few questions about minor perfomance upgrades, first off what all is available for this car , and second where to look for such upgrades.

I think I may upgrade the stereo, I would like something that fits in the stock location, I have a JVC in my pick up that rocks out, it plays mp3 cds so I never run out of good music, anyway I would like something similar for ther Monte.

Lets see minor problems, I need new cup holders for the interior, also what size are the speakers in the car.

Thanks Guys
Birge