I would start with a K&N cold air intake, that will make a huge diffrence, i did it on mine, Also another cheap thing is to get a plug and play computer, that hooks up to the obdll port and reprograms your ECU for increased performance, it even changes your shift points, im pretty shure JDm makes one, exhaust upgrade is deff. another good way to go, autozone carries some relitivly cheap ones that sound good.