Cheapest and easiest thing to do is the deckplate mod....and from there it gets pretty expensive. Don't waste your money on a K&N intake, throttle body spacers, or any of that crap...it doesnt do anything. The only real bang for the buck is the supercharger.
the airaid jr, kit is a great value, combined with deckplate, all for under $130 if you shop around. change all fluids to synthetic. or like most people say save the $1900 you might spend on all the other things that might net you 20 or so hp and get screwed!
They say they do but Toyota's have different computer systems. I dont know first hand, but everyone who has tried them that isn't selling them says they suck. I believe it from many lexus ECU stories I have read from people trying to add a piggy-back ecu on them. haha