For £200 its worth a try, if logs prove its worse the standard SMIC (which would mean it was really crap) then all you have to do is put the kit on ebay, and i'm guessing because the kit is already made up with piping etc for the Cupra then you may even get all your money back. Worth trying new things otherwise how else does the modifying world progress? If we all did the same things we'd all be driving around in identical cars....
trying new things yes, testing new things yes, posting up that its "so good" without "real" testing/proof - no