I had mentioned earlier in a post that I was thinking about trying the grove , as I did my owe version it may not be as exactly like his but close.  The Idea is to grind a V shaped grove just forward of the throttle plate , the back of the V being in a straight line with the plate, and the other leg of the V a bit more open and concave . The grove extends from the throttle shaft across the entire width at the bottom . Being forced to replace my fork seals and the disc brake pads,  the leak ruined ,I've only had a chance to ride the last couple of days, but 250 miles an two fill ups has given me some results . The best  my bike averaged over the years was 48mpg ,riding solo . riding double with my girlfriend ,combined weight 245lbs usually gave 43-45 mpg . but for the first 110 miles yesterday , and solo today at brisker highway speed (70) for 140 miles yielded the same mpg of  49.25. /or about a 9 % increase. I contribute this mostly to the use of less fuel both at idle (I had to turn the screw out 2-3 turns) and less throttle ,in all gears ,at all speeds. I've also noted less need to change gears ie. I can slow the bike to 35mph in 5th gear and speedup by opening the throttle without  "bucking " or hesitation . (not some thing I normally do ,but had to try).  I can't say it increased performance ,other than mileage, but a can say it didn't hurt it the bike ran in a normal fashion.