Welcome to the forum. I'm with jayoldschool. The base (5-speed) cars are not fast, and it's not financially responsible to spend as much as you paid for the car on mods that won't make a difference.
Quick math here.
$270 - Injen CIA
$570 - Magnaflow cat back
$100 - Shipping (from where they are in the US to where I am in the US).
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$940
Prices from
monkeywrenchracing.
If you want to make the car louder just to make it loud, throw on a fancy looking muffler, but don't waste your money on anything else.