being on the dyno is a different animal from watching your peak boost while on the road: Resitance from the dyno, no cooling air for the engine, intake, IC's, etc. The "real" numbers would only be better. I never liked the "corrected values", too hard to make an accurate assessment.
Nissan Z-cars - the best cars ever built... Go Turbo, or go home Bigger Downpipes = Bigger Man (and faster Z!)