Right, I thought it about time I updated this thread with the gaskets I can offer for your OEM+ G40 induction applications.
First up is inlet to Throttle body gasket for a 3F (GT) inlet manifold. Looks like this on the 3F manifold.
Second option is what i believe to be a standard PY (G40) Inlet to Throttle body gasket. Looks like this on the 3F inlet manifold.
And lastly is what pete was mentioning regarding resticting flow. The inside diameter (ID) of the standard G40 Inlet to Throttle body gasket measures circa 48.5mm. Which means it will actually restrict flow if you are fitting a 51mm throttle body to the inlet. Not only this, but the inlet manifold itself will also need porting work. To allow for this I have had some gaskets cut from the standard PY pattern but "notched" to allow clearance for the larger ID of the 51mm Throttle body. This gasket will also act as a template for any porting work. I only have an illustration of this fitted to a 3F inlet manifold.
So you can see how much material needs removing to make the most of an oversize 51mm Throttle Body when fitted to a 3F inlet manifold.
I will update the original post in this thread in due course. These are all in stock aplenty.