CM871 Engine cycle...

[Rock hound trucking]

i have the same trouble with my @m*m^2 any boost over 38 psi and i get a a vibraton back out of it and the vibration goes away . how can a guy fix it or what changes have to be made . i pull the mountians lots and like the extra power my pyro runs around 750 when pulling hard with high boost once a back out it it drops down just below 700