Not got into cross referencing front pads yet, but a popular upgrade for late yamaha units is to put factory honda boxed front pads on it, hundreds of reviews state instant noticeable improvement, next step is to install the actual Honda hydraulics my guess is different bore sizes for a hydraulic advantage over the factory yamaha setup. As my bike has the nissin caliper I am guessing the pads will fit. Not sure about the hydraulic advantage as gasgas may have the same bores as honda out the gate. Personally I can't imagine needing more as the brake is so powerful as it, can see some may want a lighter pull for the same effect, not myself, as even after hours of playing in the yard riding around with the front wheel locked getting used to it, my first drop was my hitting the front brake in a light left bank when I spotted a football size rock ahead, blew my front end out in a microsecond......
If you hang on a decision for a bit, I have some pics and measurements going out today to midwest mountain steve pohl is going to review and see what of his products if any, will work for the gasgas. I have used the shorty Sun dehandler design for so many years I just don't care for anything even remotely but a shorty. His levers are shorty by design, but beyond that he has designed them for a mechanical advantage to greatly increase the feel of the pull. If they have anything I'll order some in and post it.
oops, if you want some more reading on the brake upgrade, check out the yamaha forums 2 stroke section on thumper talk