Loosing boost after 4500 rpm

[Bobbit]

Ok so the FD has developed a boost leak after 4500 rpm, it only happen for the 1st few times and then everything is fine.
Basically when i give it WOT on the 1st run the first turbo kicks in fine i see 12psi no probs, but when i reach 4500 rpm i hear a loud boost leak, this will continue untill circa 6000rpm and then i get full boost, then on the 2nd pull it will leak from 4500 rpm till about 5-5500 rpm and then i get full boost all the way to red line.
Today i checked all the solenoids (2 were a bit dodgy so changed them over) and the rats nest but found no probs, so i\'m guessing it could be the crv, or actuators.
The leak itself sounds like it\'s coming from behind the uim/under the dash but tbh it could be from anywhere.
Can anyone offer any advice on what to check (or what to hit with a hammer) next?

[FD3S Efini]

did you find out what the problem was mate?

[Bobbit]

not too sure to honest. I changed a few solenoids and changed all the pipes leading to the crv and it\'s gone. Got a new prob now tho, the car is hesitating after 6000rpm under load, it free rev\'s to the limit but under load is not happy. I\'m thinking is electrical ie the spark is going out but i\'m crap with electronics so i\'m clueless as to what to check and how to check it out.