Just bought a 2006 a couple of months ago, 3600 miles on it. I want to do some HP mods so I went down today to run a baseline dyno so I would know what I was starting with. Three pulls, HP ranged from 401 thru 410, torque from 439 thru 447. Temp 66 humity 48%. Air/Fuel @ 2000 rpm was 14.5 but @ 4000 rpm it was 12.0 and @ 5000 rpm it was 10.5 . What could cause the low HP reading??? Any help will be appreciated. The dyno was a Dynojet.