I have a new Impala w/ the 3.9 on the way, I should have it in the next two weeks. I was wondering, has anyone put in any low-cost performance (engine) upgrades on theirs (ie; air filters, etc...) and if so, what is or is not recommended? I look forward to any and all input. Thanks!

welcome to the forum. good luck with your new car.

check summitracing they might help or ebay, I got my k&n air intake system for my malibu for cheap!!just dont fall for the electric superchagers.

There are many ways, but the 3.9 is supercharged so if you simply but if you put a smaller pulley on it you can add some power but don't go to much smaller or you could damege your engine. you can also buy some 2.5inch tubing and a glasspack and give it straight pipes. Altough if you don't what the car to be loud just use a glasspack in place of the muffler.

There are also some cool universal mufflers offerd by magnaflow that would fit your carhttp://www.magnaflow.com/02product/shopdisplayproducts.asp?zone=main&id=386