The problem is that the short tuned length of the Zard silencer wants less fuel at low rpm. We are finding that the tunes that work fine with systems using longer midpipes, need to be leaned down under 4600 rpm to improve performance and starting with the Zard silencer.
There have been several discussions about the issue on this site.
Let us know the outcome of the "dyno war", and post any graphs if possible.
The numbers for the Yosh piped 07 GSXR 1000 sound about right - depending on tuning. But the 750 sound low - very low. The dyno could just read a bit lower than average.
Why are the runs done in 6th gear? Did the dyno operator do this?
I generally use 5th (closest to 1:1 gearing) and the engine is loaded better. Notice that on your graph, the smoothing is at 5, and the engine is erratic at higher revs. Runs in 5th gear would be less erratic, even using the smoothing set on 2. You would only have a very slight loss due to gearing between 5th and 6th.
One thing I did notice and the guy running the dyno commented on it too was a very loud high pitched whistling sound after about 7500 rpm. By 9k you couldn't hear anything but that. A friend of mine got a short video on his phone I'll try and post that too.
Nothing in the pipe before the main baffle, sounded more like intake noise. The guy running the dyno suggested drilling some holes in the airbox. I've seen a couple of threads on airbox mods that I may try when I do the header mod but that too will have to wait for the tuneboy.
Thanks for the tip. I havent had the tank off yet but I'll go ahead and have a look to see if I can find anything. Also don't worry the last airbox I drilled was on an old RM 125 and after that it would stall in a light rain.