This sounds about right, I think I hit 18 the last time I was running and checked it.I was running a quick test on my MCS with the JCW tuning kit the other day. I was on my way to a friends to re-install my NM module and thought I'd do a quick check without it. Going ~60mph in 6th gear I floored it until I hit ~90mph. My Scangauge II showed a max boost of 11PSI. A day later after driving a few miles with the NM module I tried the same test. Same time of day, ambient temp, and same stretch of road. This time the Scangauge II showed a max boost of 17PSI.