Piping
 

I managed to get a K&N filter with an ITG Style pipe for the throttle body so no messing about with a separate breather filter.

I have been given a light aluminum 45 degree bend and a straight peice by a mate at work and I just measured the ID and it is 73mm. I have never seen them that size before.
I will need a 90 degree coupler but what size should I get? Bearing in mind that at one end it will attach to the hard plastic (ITG Style) pipe which I believe is 70mm as it was attached straight to the throttle body and the other end will attach to the 73mm aluminum pipe.
Any ideas what will fit?