I suspect I may have a small boost leak but all the usual suspect areas are dry so the only other obvious place is the outlet from the primary turbo - is it accessible from behind the wheel arch liner or the under tray? 2012 TDV8 Vogue (L322)

The outlet of the variable vane (primary) turbo is directly connected to one side of the intercooler, if you want to check that connection too you need to remove the big tray to be able to remove the smaller tray that connects to the bumper, but first remove the tow loop cover, the one with the 90 degree coin clips to have access to all the screws. The front screws of the small tray are kinda hidden by the bumper, you have to bend stuff out of the way a bit to get to them.

If this doesn't give you access to the turbo outlet (never tried that one tbh) removing the wheel arch liner is the only possible way I would think.

 2012 4.4TDV8
2000 Honda S2000

My recollection of what I saw recently of the hose with the wheel arch liner removed, I really doubt that access from below would be possible as the hose is above the sub-frame and engine mount.

Thanks Graeme! 2012 TDV8 Vogue (L322)