imco 2" shorty lower how does it help or not
 

27 checkmate 500hp good or bad bought boat with 2" shorty boat runs 65gps with 24bravo it should go faster

What rpm??
What drive ratio???
How far is the propshaft below the bottom????
Does it have trouble lifting the bow when trimming up???

1.5 ratio 5400rpms at 65mph the bow does not lift much, when I trim up rpms go up with not much speed gain, like a normal drive very large rooster tail

may actually be hurting your top speed, they only sure fire way to prove it to try a 1 or 2" spacer, which will give you more bow lift

What prop are you using? Is it a bow lifting prop or stern lifting prop? I normally use a Mirage plus (bow lifter). I borrowed a friends Hydromotive 4 blade (stern lifter) and mine did the same thing you are talking about.

The shorty is definately hurting your performance. Try 1" to 2" spacers to lower the propshaft as Random said. The Bravo prop is not the problem.