Arne, I also have been looking at available parts to build the stacked tip exhaust, but was missing the dual out separation spec on the Magnaflow 11148, thanks for sharing. I believe the last company to offer this bolt on arrangement for a Z was Monza (Pacesetter) which no longer makes it, they do however still sell the slash cut resonator tips (see link) in various sizes, that as far as I can see in the pics, can be cut to length and welded on the Magnaflow 11148. http://www.pacesetterexhaust.com/tips.htm