I have a 1990 240sx blacktop s14 sr20. i have her at the shop and the build has...87mm cp pistons (already had with my gt2871r set up) tomei 270 cams greddy plenum greddy FMIC greddy t67 turbo kit msd 72 lb injectors (previously with t28) walbro 255 spec flywheel and stage 3 clutch and looking to go with the Enthalpy tune. I'm not worried about studs or gaskets since someone has been down there to do the piston install or should I? I'm looking to get 500whp do you guys think this is possible with everything I have put together?

from the looks of the chart on greddys website that would be pushing that turbo to its limits. looks more suited around the 350-450hp range.

450 on a 25g turbo.. I was under the impression of 500-600 hp. I may be wrong.

You'll have those injectors maxed out and still need more. I plopped your power goal and other relevant info into witchhunter.com's injector calculator, and even at 100% duty cycle, you'd still need 88 lb injectors. The only assumption I had to make was flywheel HP at 588 accounting for the standard 15% power loss through the drivetrain.

At your power goals, you most certainly should invest in head studs. Factory bolts are likely to stretch at the wrong moment, especially if you reuse the old bolts. Choose a quality head gasket and you should be good to go. I'm not sure if you'd need main studs. You'd have to do some research on the necessity of main studs for your goal. My rule of thumb is to take into consideration your end goal, and then build a motor that can handle more to give you the extra head room you need.

My sr currently has 57k the bottom end, bearings and valve seals were done at 50k buy previous owner my guess is that my hg and studs should be upgraded since I've been boosting 15lbs all day on my turbo? But in the end my goal isnt near where im currently at. "better to be safe than sorry" but its still questionable slightly.