I do have a V4R. The part numbers for the detent spring on the x99 and V4x are the same. The factory pro has the same profile but a lighter spring rate. The dimensions of the shift lever are also the same, just ceramic bearings. There's a lot of the same hardware carried forward, I say it lightly but its really just the addition of 2 cylinders and the associated hardware.
The "sticking" of the lever I find in 1st and 2nd gear during downshifts is what I'm hoping to allieve, also to help set it in neutral easier, with a the lighter spring rate and the lower friction bearings