losing supercharger boost

[barrington]

hello hope you can help, my son is runnging a mini cooper s supercharger setup on hes car and has been running fine for a while but have noticed when you get high up in boost it dies off sounds like a air leak but iv changed all the gaskets with new ones and checked pipes and all seems good. is there anything else that could be the problem where the leak could be. didnt no if it could be the intercooler pipes or the actuater?

cheers dave