300 dollars.....u can get a real aem cai like stated above, find a real good deal on a custom piping catback exhaust, or get a high flow catalyc converter. I wouldnt really suggest the custom exhaust because with 300 dollars, the quality will be shit and muffler selection will be very limited with ghetto ones and sound wont be all that nice either. 300 is too little to actually make a noticeable gain.