My throttle body leaked a terrible amount, enough to notice the car running extremely rich under boost once the air started to leak out and the fuel mixture became incorrect.

The solution? A Hypertune SR20 billet throttle!

Hypertune of Australia produces an all billet throttle, 66mm ID, features sealed bearings, and is available in any anodized color.

Fully adjustable pulley

Adjustable throttle stops (open and closed)

O-ring seal (no need for a gasket)

A modular TPS system, meaning ANY Nissan tps that they have an adapter for can be used

Here is the throttle with the KA24 TPS adapter installed, which is the exact same TPS that the VG30E uses. (The adapter can be clocked in any direction, for fine tuning, along with the regular adjustability of the TPS)

It bolts right on to the factory plenum, which has a bolt spacing of 60mmx60mm squared:

If you are interested in acquiring a Hypertune throttle for your Z31, you can click here: 

https://affinismotorsports.com/collections/nissan-datsun-300zx-z31/products/hypertune-throttle-body