[Raptor]

The higher compression isn't surprising, the head was milled >.010" and the valves are larger than stock, they are flat on the bottom instead of having the small dish like the factory valves. Both of those things will contribute to a little higher compression numbers. The leakdown test like allan mentioned is really the next thing to do to see where the varience in coming from.

Injector seals don't cause compression leaks, they are inside the intake runner and behind the valve so they have no effect on compression. They can leak boost like you found of course.

The last thing is to obviously make sure you are using an accurate compression tester. Lately we have seen some really bad numbers come from cars that were fine due to people using junk testers. Use an equal number of revolutins, throttle blade open etc.