as far as in cost there really wont be much you can do to get 400 to the ground, u can try CAI like volant or lingenfelter. Dont get a K&N ive been hearing really bad things about it. Course if u want to go the hard core rout that does about the same as the CAI kits, it just dosn't look as nice. for 400 id replace the rockers, CAI, exhaust, 36lb injectors (w/ plugs to match)and custom programing, should put you there with about 400. Once you get a exhaust, do a cam then reprogram again. That should put you around 450. Im not to much of a NOS man myself. I like power when ever i want to touch the peddle and not have to go refill all the time other than gas that is

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