Received my Greddy copy plenum the other day and was surprised by the speed. Definitely UK stock!!
Came well packaged and with fittings and o-ring etc. Looks well made TBH.
Only issues are:-
1. Some casting excess inside the main chamber. An hour with the die grinder sorted that out.
2. The mating faces for the two halves of the chamber aren't exactly 100% true. Nothing that a quick trip to the local machine shop won't cure.
3. Groove for O-ring varies slightly in depth so a thicker one might have to be sourced.
All-in-all, for £110 delivered I'm not exactly spitting the dummy!!! Machining will probably cost me £20 or so and an O-ring should be a quid or two. Also took the time to drill and tap the 1/8NPT thread to take the water/meth nozzle.
Considering that a gen Greddy plenum would be typically around £ 500, I'm more than happy to sort out the niggles for the considerable saving. Again, it's not that I CAN'T afford a genuine one but I'd rather pay less money for the same thing (niggles notwithstanding!!)