Its strange how poor the std intercooler is at exchanging heat, its a massive intercooler at 600x440x30 but it isn't in the ideal location in the rad pack, I moved mine to the front in one of my early experiments:
results showed IAT dropped to 60c from 70c...yeah not great for all the work...so intake dropped to 60c with ambient of 28c and 26psi boost.
I later installed a much thicker core with better internal design which made the biggest difference as Nutron says this is essential if your going to hit 300hp from higher boost in the future, and this follows ambient with just a few degrees difference at 30psi.
However, attatched is an early dyno that may be of interest with Std turbo, std intercooler in std location, std exhaust with dpf delete. F1 remap, egr delete, iirc boost is 26psi.
3 runs show a P-box (plug n play tuning box), second run is with F1 remap, 3rd run is F1+water/meth.
I wouldn't go higher than 26psi my self on stock intercooler, it has crimped end caps that will probably fail, so 270hp is about whats possible with help of a little water/meth....if you want 300hp its cheque book time I'm afraid!! and if you read on in my thread you'l see how much is involved for another 30hp...not sure its worth it!