I have the 10% one in my R34. I'm still building the car so I haven't driven it yet, however its installed and I would say it makes a huge difference. It really is almost solid, where as the rubber inside the shaft on the old one was so soft there was a huge amount of flex in it. Obviously this will come at the expense of NVH but I think it will be well worth it as the standard skyline boxes are not the most precise units.