Originally Posted by Jordo!

First part isn't quite right, at least based on about a dozen or so Nismo vs comparably modded/tuned non-nismo Z's I've seen dynos for. The fueling and spark profile will not adapt to match the Nismo's without tuning.

Yes, it will. It takes time and a willingness to actually go to redline @ WOT a number of times over a few days to get the ECU to re-learn. Can be sped up by clearing the learned fuel data at time of install. My baselines with drop ins and the Nismo CBE were well over 295 WHP with AFR's right in line with factory specs. That's not possible if the ECU hadn't re-learned fuel data sufficiently. This is before I had an UpRev license installed.

Also, I thought the Nismo does have a slightly higher rev limit as well -- I could be wrong on that one.

I've never heard of this, would like to see evidence from UpRev to support. (Screen shot of stock ROM)



I also remain convinced that the Nismo has slightly different VVEL tuning as well -- although that is yet to be confirmed (hello, GTM?) -- after viewing these dynos I've been accumulating from various folks (all dynojet, BTW).

Unless you (or anyone) can provide UpRev traces showing VVEL actuator behavior that is different, I'm gonna say it's all the exhaust you're seeing. The H-Pipe design absolutely causes the high end of the curve to take on a different shape, as compared to the stock Y pipe. That shape is visible even in my own dynos with longtube race headers + the Nismo OEM CBE.

However, I agree 100% that picking up any Nismo exhaust new is not needed -- get one used for modest gains and good sound without any unexpected rasp or fitment issues.