I'm no expert on Vmax's. I like my 2017 Vmax in its stock form, Runs Perfect, no surging or anything I have read about that others have had. Mine is a bit slow picking up speed on the low end but pulls hard and steady after the about half throttle, I am comparing it to riding a ZX14R. It's like it has a delayed throttle response or something, maybe because these bikes are so heavy.
*The only thing I would be interested in, with a Nash Flash is if I could get a much quicker acceleration in the low rpm range.
I had a New 2017 Kawasaki Zx14R in 2017. That bike was Way Faster (noticeably faster anyway) in the low end than this Vmax is. It was about 200lbs lighter though to if I remember correctly.
That Stock ZX14R had 3 power levels the owner could adjust as needed. When that ZX was in the highest power position (I don't remember what the 3 power levels were called) it would flat out FLY!! It would Definitely beat up on any Stock Vmax 1700. Hard really to describe the power delivery on it.
It would have been So Cool if these Vmax 1700's had come stock with the 3 level adjustable power, wouldn't need the flash.
When I give my Vmax Full Throttle it feels to me like the power/speed is trying to catch up to my throttle position.
I Love the Rider Position on my Vmax. Very Comfortable, I could ride all day on and not be sore.
(I had to sell that ZX14R cause my neck would really start hurting trying to look up/forward all the time in that sitting position. I really enjoyed riding it though.)