1KZ not boosting?

[RS13]

My BIL's Surf is having issues with not producing boost, he has had it in to a mechanic who replaced the turbo with a known good one and manifold gaskets with nil fix. I'm yet to see it, but as my sister tells me it makes a loud "whistle" (still runs well otherwise, just gutless) I'm picking potentially a leak in the intake piping/manifold somewhere, unless there is something else that could cause this on these motors? Its' a 1KZTE, not intercooled, with 400,000km. He isn't the most mechanically inclined person hence guessing the turbo/manifolds.. the "mechanic" he took it to couldn't find a fault but he also snapped several studs and metal putty'd them back in so I'm not putting much faith in his abilities.. haha.

As usual, any advice/thoughts, much appreciated, thanks chaps.

[85AW20v]

Blocked intake or exhaust?

[RS13]

Inlet manifold has pulled studs. Needs helicoils.