top end power lose

[srad]

wondering if anyone can shed some light on my issue.I have a 20v black top 4age engine that used to dyno 120.3hp at the wheel running a razorback computer. i changed to a motec m4 computer and have now lost 11hp at the top range from 6500rpm to 7500rpm. we plugged old razorback system in and still did not produce anymore? had compression test and lealk down test and all are perfect so not engine......just wondering if VVT is having issues would love some feed back to see if anyone has had same problem or could help with some useful pointers. Dyno people had no explanation to issue of power loss at the top. all of the torque before 6500rpm is same as before however once it reaches 6500 it flattens out and falls away

[srad]

i forgot one thing vvt is set to turn on at 1700 and turn off at 6000 the dyno guy said its all workin fine but could there be a issue with it turning off