I had EZ+RV275s and could peg my 30lb boost gauge (HX35). I think it's more a matter of fuel+load than air temps. Empty and level, can't hit 30. Empty and 6% grade, can hit 30. 5th wheel in tow and 6% grade, can peg and hold, but always back off the throttle to keep the boost where I can see it.
Now that I've upped to Mach 1. 6 injectors, I'm getting a 60lb gauge.