please help!

[tomrex]

can anyone shed some light on a problem i\'m having!
after collecting my rx from having a new inlet manifold gasket its been making a loud noise when the turbos come in, which sounds like a cross between a large boost leak and a belt slip.  But it\'s not loosing any power.  It first comes in with the first turbo then fades out when the turbos are switching, then back again with the secound turbo.  I\'ve taken out the air box and all the boost pipes (big ones), and the elbow going into the plenumn.  They all look fine.  So i\'m lost for what to look at next, as i\'d rather fix it myself if i can than take it all the way back to Portsmouth! any help is great!!
confused:

[tomrex]

the problem is somewhere in here!