Just for grins, I thought I'd compare a tuned dyno (later re-tuned for more a bit more power) of my 2010 Z vs my 2011 Z given that I happened to have two with very similar ambient temps (over 95* F!).
Note that the lower peak values dyno (2010 Z - titled "Summertime baseline") includes some tuning with uprev (tweaked AFR and ignition advance), smooth tubes, K&N filters, test pipes, and the S-tune exhaust (w/Y pipe). The humidity is nearly twice as high...
The higher peak values dyno (2011 Z - titled "K&N Nismo catback") has stock AFR and ignition timing, smooth tubes, K&N filters,
FACTORY CATS, and the Nismo take-off exhaust (w/H-pipe). It also has lower humidity helping it a bit.
Air temps and air pressure are about the same. Same dyno, same shop (Proven Power, above ground dynojet).
Below are the values both SAE corrected (compensates a bit for different humidity as much as anything) and also uncorrected.
In the immortal words of Arte Johnson, "Very interrrrrrrresting...."
Interpret as you will.
Detailed comparison, SAE corrected.
Just comparing when hp and tq are (about) equal, no CF.
I dunno -- it's still inconclusive, but I'm thinking the S-tune exhaust kinda sucks as compared to the Nismo take off. Given how similar values were until higher in the rev range (with SAE correction), I'm not really convinced that the Nismo take off is simply benefiting from dynoing on a day with less humidity...
I think it's just a much better design than the S-tune exhaust.
Thoughts?