I might be able to pick up a set of GT40p heads and upper/lower intake for $350, what kind of gains would i get if i just threw all of em on with the stock cam? Would i need to upgrade injectors (if you can with SD) What all would need to be done?

stay with stock injectors. cant change em with sd somehow the computer wont like it. it might all fit in. im not sure though im still new at this but im sure the sd pros will help you out on this pretty soon :)

the flow of the 40p head is better than the stock e7's . far as power i would recomend changing the cam while you are at it .
yeah the injectors have to stay at 19lb an hour because the ecu in the sd cars are based on preset values it will not reconize the 24's and so on unless you upgrade to megasquirt ecm or an xfi by fast .

GT-40p heads and intake will work great in your car, and you have to stick with the 19's unless you get someone to reflash the computer or go with a stand alone computer. Bump your fuel pressure up and advance the timing. Also keep the stock cam for drivablity but advance it 6 deg and add a set of 1.7 rr to increase the lift from .444 to .471. The thing will be a blast to drive.

evrything you said is correct

thats a good cheap way to make some good power

go ahead and change the cam. buy the stuff, put it on. You will have a totaly different car for only 500ish dollars

or buy them and sell it for alot more

Ill buy the heads if you dont want them:D