what is the max psi my 2003 gt can handle? it is stock with the exception of highflow intake and exhaust

 

I wouldn't run anything above 9-10 psi on a stock 4.6 2v. Anything above that, they tend to start having real problems, like "need a new engine" type of problems. With ported heads, blower cams, and other supporting mods you should be able to achieve around 450rwhp "safely" with a good tune, but nothing is guaranteed on the stock bottom end. Mine blew a ring land at 400rwhp on a safe tune.

 

I think you also need to keep careful attention to boost temperature. The hotter the charge the less PSI you should be using on a stock engine. Maybe 9-10 would be OK withintercooled boost, but 6-8 if not intercooled

 

Correct, I forgot to mention that is when intercooled. Although, there are a couple people on here running 9-10 psi non-intercooled without any issues, I wouldn't want to try it.

 

9lbs. non intercooled, runs like a charm BUT, getting the aftercooler put on this spring with a little more boost.