IPD Y-Pipe is a source of debate. IPD says it improves HP etc, everyone who has bought one says it does nothing but lighten the wallet.
There is a guy by the name of Fisher Motor Works on the Cayenne tuning group on facebook who is 3D printing a version out of carbon composite. It's still in testing - and has been for a while...

 

Yeah totally makes sense. I was skeptical immediately reading the IPD Plenum claims of 30+hp or whatever. I thought there's no way that y-pipe is that much of a bottleneck. Granted, the intakes to/from turbo/intercooler/throttle body seem pretty tiny IMHO (I mean, 2.25"? come on) but still...

Do you have a link to this Cayenne Facebook tuning group? I'd love to check it out. I also plan on asking Hanksville Hot Rods shop who makes lots of Cayenne fabbed exhaust and intake stuff if they'd be interested in making a y-pipe plenum of their own and/or maybe just a throttle body spacer with an NPT thread nozzle for my water/meth plans... they happen to be sorta down the street from where I live too. We shall see. https://www.hhrproducts.com/porsche-...-2011-to-2018/

 

https://www DOT facebook DOT com/groups/294249544886761/members/
(it's not letting me post a direct link for whatever reason)

And ahh, you should also search within that group and the Cayenne Owners and Cayenne Support groups about HHR too. Short story is they aren't making anything.

 

I'm being told this is actually a MAP sensor now, and not a MAF sensor?