I'm not sure how Nissan runs their engines while on the Dyno. Meaning im not sure if it has full intake and exhaust bolted to the motor during the time of testing. If that's the case then yeah I could theoretically see the extra 2hp difference coming from that change in sizing.

Just an update to this thread. The stock exhaust I had lined up fell through. Shipping is just going to be a bit much for a stock exhaust that im pretty much just hacking up. I am waiting for a local sale to pop up now.

*Update*
If there is still any interest in this project I have found an 08 G37 coupe mid-pipe and muffler earlier last week. I was able to nab both for $100. While it looks quite dirty in the pics, it is pretty much rust free. After examining the resonators on the 08 G37 coupe to my 10 370Z. They are indeed identical beginning part numbers. With the following numbers/letters regarding its vehicle fitment.

The only fitment issue with the G37c exhuast are that the tips stick out nearly 2" from the bumper on a Z. A simple fix is to cut the factory tips off and either reweld them shorter, reweld Z tips on or source and aftermarket tip. I went with a bolt on style tip that is the same diameter as the stock ones but, in the burn blue finish. Pics below of mock up. I will be installing it sometime today and will get before and after vids for comparison.

http://www.the370z.com/members/fanta...0z-exhaust.jpg
http://www.the370z.com/members/fanta...t-tips-cut.jpg
http://www.the370z.com/members/fanta...st-mock-up.jpg
http://www.the370z.com/members/fanta...nted-final.jpg

All done!
Looks and fits great. Vids will be up shortly. I did however hear a VERY distinct buzzing sound coming from the muffler upon initial startup. That leads me to believe I got a G37 coupe muffler that did NOT have the TSB for replacement done to it. I've started my Z twice since then and haven't heard it again but, it was indeed there. I'll monitor it this week and see what can or can't be done. It would suck for all this work to be done and it all still fail on me. Enjoy the pics for now.
http://www.the370z.com/members/fanta...-installed.jpg
http://www.the370z.com/members/fanta...ting-great.jpg
http://www.the370z.com/members/fanta...tips-flush.jpg
http://www.the370z.com/members/fanta...0z-exhaust.jpg

Good stuff broham. Get the exhaust note you wanted?? And I saw the pic of the 240 exhaust... damn you keep up with pictures haha.

So far...yeah I got that famed VQ note back. I just hope that buzz/rattle I heard at start up doesn't become an issue and of course I do haha
Gotta keep track of those cool little projects.

Awesome man! I think im just going to bite the bullet and buy the MD when the first rolls around.

Hell yeah man! Best CBE out there IMO. With MD in GA now maybe you can pick it up on the cheap haha
I was 99% set on MD before I bought my wheels and now with this project, hopefully I'll settle for awhile. I think a full on exhaust is a bit much for me. Sensitivity to drone and sensitive hearing is why. Partly why I got fed up with my old Invidia/ART setup.

Really? I didn't think it was that bad. I still plan on sound dampening the entire interior so that will cut some drone out.

Yeah drone was still there. That's on me though. You plan on audio mods so, dampening will be an awesome addition anyway. I'll help install lol

Btw...I heard that buzzing/rattle from the G exhaust thus morning. Seems to do it on cold starts.

hmm... what was the TSB for? Anything you can fix yourself for relatively cheap? And I plan on using the RAAMAudio mat. Its a large car kit that comes with dampening stuff (like dynamat) and a thin foam over the top of it. Check it out.

http://www.raamaudio.com/package-2-3...ensolite-foam/

The TSB was for a buzz/rattle coming from the rear exhaust canister on the G37 coupe models. I knew that going into this project and it sounds like that's what has happened here. As for fixing it myself, I don't know honestly. It's an internal rattle which means opening up the G exhaust to fix it. Seems like quite the hassle right? Guess I'll find out more on the way home today.

I like the idea of that RAAMAUDIO mat A LOT more than dyna mat. The foam is a nice touch and definitely helps. I'll check it out.