F'ck me they're even cheaper than I've been paying and they'll do the job perfectly, although I usually buy the brown ones like the original items. Here's another tip you can use the brown ones as gearbox shaft/clutch pushrod seals and they are Bomb proof. Steve R
They all look the same to me the only real difference (apart from the smaller exhaust valve cover on the SP and the porting on the G and SP heads) is the shape of the '91 851 combustion chambers and the chamber capacity of the rest. The 748R heads have wider spacing between the guides*, 996 heads have different barrel stud spacing and different combustion chamber shapes. I've never seen inside ST4/ST4S so can't comment on them. *Why the factory did this I don't know as my "G" Corse heads have 37/32mm valves without the guides needing to be moved outwards. Steve R
If you scroll down on the link you posted to the green ones the brown ones can be found and they're 82p each. I buy them from my local engineer/cylinder head performance specialist. Steve R
