Hi Tom,

Contrary to popular belief, the plain H89 (double valve springs were the exception) was featured on the A14E (which is the more common EGI a-Series).

The A15E featured the twin outlet exhaust, just like the A12GX and A12T manifold only very slightly better flowing thanks to some slightly larger ports. I believe the A15E featured the H92 cylinder head which had the small injector stream notches at the port mouth (roof).

So, in all fairness you won't have to notch the cylinder head as the A14E featured a H89 without port notches. And looking carefully at the angles there is adequate clearance. I suspect the port roof notches were a later development what benefit they brought I don't know exactly.

I shall endeavour to upload some documentation to this thread, when I can.