I'm not sure about your truck but my friend on his 06 is pushing 59psi with the stock head gasket and head bolts. His ARP head studs are in the garage waiting for me. Sorry about the cool down feature. I thought it was the same as 06.
50 PSI is the max most people will recomend for a stock engine so your buddy is pushing it.
Also consider the turbos MAP range, beyond a certain point on any turbo the boost doesn't supply more air it just gets it super hot, the hot air expands giving you bigger numbers but not more air.
I think on the 03-04, 27-30 is the max usable boost pressure, 04. 5 and up has a bigger turbo and can go higher.