Are you saying this from the dyno graph or from in the car trying to look at gauges? Your Graph shows RPM till 8100 and we know you didn't spin it that hard. I figure they used roll speed for RPM pickup but was this is 3 or 4th gear? Using roll speed you normally end up +-200rpm but not 1000.
On my Mustang dyno I would expect your car to make right around 390-400hp. I do not have any corrections in it to make DJ numbers. Did they say the 17% is already added on your graph?
You need more data before you start tearing your car apart just because you didn't get Dynojet results..