I installed 14gr sliders and a new drive belt at just over 5,000 miles. It was too early for the belt, but I thought it best to install one once I was in there.
The GTi is the third scooter I have them installed in, and they really do give a smoothness that isn't there stock. I don't know about acceleration or top speed, as I have not gone to the bother to find out. From what I have read the sliders will outlast the rollers by 2X or 3X, and, as stated, offer a smooth ride. The other two scooters I have them installed in are a Vespa 300GTS and a Yamaha Morphous. The Vespa certainly shows the advantage of sliders from an acceleration standpoint.
It is extremely important to install them properly, not from a damage standpoint, but from a performance standpoint.
I know they seem to be to good to be true, but Dr. Pulley sliders are really much better than rollers.
Karl U
Las Cruces, NM