i bought a 2mm decompression plate from ferriday engineering.and a felpro headgasket for my old black s2.it worked but when car went in to be set up at jamsport,jamie advised me to throw it away.reason i got it was because head had been skimmed way too much.it was sat on the block with some sealant and the head gasket laid on the top.in the end we put a different head on it and threw compression plate away.
think it would be better to buy low comp pistons or maybe have slight skim off the pistons if your on a budget mate.
the plate cost 160quid with the gasket,id rather have spent that towards new pistons tho really.