Close, they are GREDDY items. Originally designed for thier 700-800hp low mount T618z turbos (im not a fan, to big, too laggy) they found shortcomings with the twin elbow design and they found out that when fitted to the smaller T517z's there was noticeable gain also.
and yes mongrel to fit, but can be done... i dont advise fitting any brand of dump with the turbos inplace. It is a fairly quick and easy job to get the gtr turbos off if you follow a sequence.... definately some tricks of the trade.