We just put a procharger and cam on a 2011 corvette Grandsport. Everything in the tune is fine except when we are trying to dyno it. It pulls great until we get to like 4800 rmp it then just drops its power and sounds like someone is putting there hand over the exhaust. after it drops it continues to grow again but not near how it should. The line graph looks like a automatic car when it down shifts on a dyno. There is no change in the boost when this happens. It is still rising. We only have 6psi. Any ideas?