The standard intercooler outlets are 60mm external diametre at each end.
The standard throttle body is 63mm external diametre.
The T3 & T34 turbo outlet is 51mm external diametre.
The T3 inlet is 60mm external diametre.
The T34 inlet is 70mm external diametre.
The T38 outlet is 63mm external diametre.
The T38 inlet is 70mm external diametre.
The T4 outlet is 63mm external diametre.
The T4 inlet is 76mm external diametre.

The problems occur with the hoses when after market intercooler manufacturers make both outlets straight out at 90 degree's.
The standard intercooler outlet on the turbo side is angled towards the wing.
The standard turbo to intercooler hose will fit but it has to be cut down. for straight outlet intercoolers.

PS i manufacture polished stainless steel boost pipes for this conversion.

Hope this has helped.

Regards Paul.