turbo/boost problems

[RemarkLima]

Have you still got the air pump? Mine\'s pretty loud especially before everything\'s warmed up. But then it cuts out after 2500rpm.

Otherwise if it\'s not an air leak it could well be the check valves as well.

[Johnerz]

yes, the air pump is still on.  the engine is standard apart from blitz dump valve and blitz filters.  ill check that alter as well.  
 
im pretty sure that it could be a hose due to the hissing i hear, etc.  couldnt find anything on an initial inspection but ill get all the pipes of and have a good look

[RemarkLima]

And you hear this hissing above 2500rpm? As my Air Pump sounds like an air leak while it\'s running...

...Maybe make sure it\'s disengaging properly as well, open up the bonnet, and rev the engine with the throttle cable, then check the pully on the far left (behind the air filters) stops spinning above 2500rpm, well just the centre section should stop spinning, not the belt!!!