Nobody has one off the car to confirm the measurements for me...? :o

No rush... but would be greatly appreciated and worthy of rep points of course :tiphat:

Trust me dude lol

OK I'm confused LOL

What size are the stock Y-Pipes, and are they the same on the Nismo?
2.25" or 2.5" inlet - to - 2.75" or 3" outlet.

I'm getting a JDM Y-Pipe (2.5" to 3"), which I'm sure is a direct bolt-on.
Am I going to gain anything now from getting a 2.5" to 3" Y-Pipe ??

Is the 370z OEM exhaust same as the G37? If so, I had the same question for my G37 and here's what I've found out so far:

Exhaust diameter question re: Berk HFC to OEM mid pipe - MyG37

I'm not sure the stock Nismo exhaust (NOT S-tune) even has a Y-pipe.. right??

The Nismo has an H-pipe according to Nissan:
"NISMO-tuned dual exhaust with H-pipe configuration"

Yep -- see here

Difference Between Regular 370Z exhaust vs Nismo 370Z exhaust - Nismo 350Z / Nismo 370Z Enthusiast Community

Great answer thanks :tiphat:

Guess I have a spare Y-Pipe for sale now, dammit..!!

Which design yields more power, the Y-pipe or the X-pipe ?

x-pipe = more top end power from what I've heard

Kinda makes you wonder why Nismo went with H instead of X like almost every aftermarket CBE vendor.

From the testing Stillen performed, they found that a Y pipe design yields the best gains on this car in both hp and torque. I personally think that choosing between an h pipe/y pipe/x pipe is splitting hairs on a performance based view point, but the sound they produce is different.

See my posts and links in this thread http://www.the370z.com/intake-exhaus...mo-h-pipe.html

I believe you'll also have to change the mid pipes if you want to use a Y-Pipe on the Nismo.

Not sure there any any real cheap solutions here guys.

As someone mentioned at the point of changoing the downpipes and mid-pipes, you may as well go all out, and just get a full cat back that performs better than the Nismo LOL

Plus you should through in some Berk HFC's :tup:

Just measured my stock Y pipe for you guys... My measurements for the inlet and outlet diameters of the stock Y pipe are as follows:

Cat to Y pipe: 1 3/4" for both inlets of the OEM y pipe
Y pipe to axle-back: 2 1/2"