Okay so recently I picked up a complete GSR swap with 120,000miles for $200 at a junkyard. My plans are to rebuild it, and go boost. My question is, how extensive should the rebuild be if I'm only planning on making 250-300ish hp? Price isn't really an object because I'll probablly do the build over a span of a year, but I'd like to know what I should be replacing or keeping in order to get a reliable 300hp out of it. Like would I need better rods, could I use new oem pistons or should I get lower compression ones? Also for the head, would any valve train/head work be needed? Thanks guys, appriciate all help.

 

plenty of info on this already so many may not reply... however my friend has had 325 on a stock gsr engine for years now.... you could do forged pistons and rods,
my setup is
gsr with stock cams
skunk 2 manifold
spooling manifold dp
backdoor intercooler
4bar map
benson sleeves
9:8 cp pistons
eagle rods
supertech valve train
70mm tb
garrett t3/t04e 60 trim
650cc injectors
8 psi 325 and 15psi 375
plan on swapping injectors and turbo and going for more power