Yes, Koni has a lifetime guarantee, but it's worthless. You can only get the strut repaired or replaced AFTER you send in the strut and all mounting parts, as well as proof of purchase, blah, blah, blah. How do I get around while I am waiting for Koni to determine if the blown strut is covered, then wait for them to repair or replace it. Worthless.
I think I'll go with 2 new struts.