I have put the DP Sliders in my 2011 downtown 14gr and they are fantastic. From the line and mid range much improved. Top end about the same. 15 would drop the rpms some on top end and probably give a little more speed at the detriment of low end performance.
Having said all of that I want to speak up on the topic of Sliders versus rollers and the comment about ramp geometry not being congruent. THAT is not true 95% of the time on all scooters. Sliders are an awesome and a no brainer improvement that almost without exception provide improvements in a couple of ways. I don't mean to take away from anyone's opinion or preference but this has been the real world experience I have had.
I have had sliders in my Downtown 300, Burgman 400 (30k miles), HD 200 , majesty 400, BV 500, people 250, Honda Helix, MP3 250, MP3 400, MP3 500, ridicuous amounts of Chinese bikes and had excellent results without exception. Some of these bikes for 10-30 K miles. Some of these were group members bikes. More info avail upon request.
I now own a People 300 and am about to put sliders in it. Don't fear the sliders they are ROCK solid...in the one catastrophic failure mentioned on this board there could have been extenuating circumstances that could have caused it. Again not trying to tear down anyone's experiences or comments but rather calm any fears and set the record straight on Dr pulley sliders ...don't by clone slider IMHO.