Originally Posted by JonnyBravo

Better flowing exhaust and ram air effect. Exhaust being the main reason for the reverse head apparently.

There is a Swindon reverse head engine for sale, has been for sale for ages, only 8k I think last time I saw an advert for it which is shockingly cheap for something that was capable of 300hp

Originally Posted by dovboy

something to do with the ram effect on the trumpets/more direct flow

and as said,smoother exhaust route/flow