Are these any good, obviously wanna do the stem seals when I do the heads, do I stay oem or go uprated if that's what they are 

I'm running a full supertech valve kit in mine, valves, buckets etc etc etc

Although supertech stuff is good quality, I was advised that the oe stem seals are good for 500 hp +.

Especially if you use the exhaust valve seals on all the valves (intake valves too) ,as the exhaust valve stem seals are made from a better quality vitron rubber to cope with the heat compared to the oe intake stem seals [emoji6]

Yes, did read that savs, may order two sets of supertech then and use them on both, maybe the seller will do 16 exhausts