Also be weary of the "guaranteed for lif" ploy...That rarely holds as true as it seems...I am betting they are guaranteed against manufacturer defects, but not against normal wear and tear from a driven car...It gets tricky...If they blow out for some unknown reason, then they will probably replace them...But if all 4 struts are showing problems do to extremely stiff spring rates, they probably won't cover them...Bilstein does the same thing...and realize that no modern strut will last forever...They all wear out eventually with enough driving and bumps...But look into how KYB's guarantee is issued...To my knowledge they are not performance struts, and are not designed for other mods made to a stock suspension...so I would bet if other than stock springs are used, they won't cover them...