cold air intake

Don't get a CAI that locates the air filter in the engine compartment. They will often cause a surging idle. Besides that, they suck up hot air from the engine. The stock setup is surprisingly effective as a CAI. Spend your $$$ on some traction mods or subframes.
 
Anderson makes a nice CAI. Its the only one id ever buy.

http://www.andersonfordmotorsport.com/
powerpipecar2.jpg
 
pjb I guess if I find one used for cheap. But I would rather spend the cash and get a nice painted one. Funny I just picked up a '06 elantra for the daily driver, nice little car.

I bought mine new last May and now it has over 29k and it hasnt been back to the dealer once for warranty repairs. Im still on the original brakes and even wiper blades. Its been a great car so far and hopefully it will continue to be. It gets double the gas mileage of my Mustang.