dropping in a k&n air filter onto your stock hose (replacing your air box)
won't exactly give you hp gains, but it'll only cost you $70, and give you better throttle response... I'm not 100% sure the part is the same for a LS as it is a GSR, but if you want the K&N Air Filter that'll fit, it's model number is "e-2427"

someone correct me if i'm wrong.


Without spending "a lot of money" you're not gonna find a whole lot to do..
maybe some altezza headlights will put a couple more ponies to the pavement, if you tune them right... don't forget to check your blinker fluid while you're at it.