Yea it's a S1 RS4
I can't remember who I bought them from, a UK based tuner probably - would have been about 4 years ago.
Will give autoextreme a look, thanks.
I've never heard of that brand lol. I've been on skylineowners for a while so tend to read up on stuff there, it's just people on here know a lot more about the Stagea.
I'm in the UK so import taxes would make them more expensive.
I put a different set of yellow jackets from my mates R33 in which ran fine but I think the plugs maybe part of the issue.. It'll accelerate fine for the most part but will have a rapid misfire under boost/hard acceleration. I'm going to double check everything else that I've messed about with too (loosening of pipes to get at coils and the 2 stage high boost mod).