As far as I’m aware I was the first to fit a spacer to my YB (At least here in Australia) way back in 1996. At the time my engine had a stage 3 Mountune kit running 22psi. I had a Pace RS500 ‘cooler and 3” Exh system. On the dyno it made an extra 16hp to the wheels. There was no need to remap the ecu.

The main idea of the spacer was to increase the distance between the trumpets and the inner wall of the plenum as this is only 10mm. The only reason a 15mm thick spacer was used was due to the fact that the “bosses” that the fuel rail bolts to are 16mm thick and once there is a gasket on both sides of the spacer the total thickness is approx 16mm meaning no need to add any other parts other than a modified an “L” bracket that connects the Throttle body to the engine mount cos the Throttle body is now 16mm further out.

The spacer plate days are now old school compared to the manifold we play with these days





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