kyb voids the warranty if you drop your car over 1 inch. This is for all of their struts, so the AGX's are included. (last time i checked anyway)

I have kyb gr-2 with prokits...it performs well. On flat roads, it isn't bumpy...almost a stock feeling, but much better cornering. On rough roads, though, they feel like any other aftermarket struts...you'll feel it all (and I have stock tires)