Head gaskit

I could not agree with you more steel wisperer I have never found a head gasket that didnt benefit from a retorque and that includes the gaskets like felpro that say they dont need to be retorqued.
I have been working on BMW motorcycles for near 20 years and with the water cooled K series if they show signs of head gasket failure a retorque even at 100K will hold off a change of gasket till a more convenient time. I even did that with my 6 cyl ford engine.
Its not the recommended thing to do but it does buy a bit of time and always worth a try.

Unless anyone can name an aftermarket gasket that has gone the distance (say 50,000 miles or so) I would stick with OEM Kawasaki.

Use "Lightspeed" at your local Kaw shop. This program (Most dealerships have access to) locates NOS on dealership shelves. It takes a good parts manager to make you aware of this resource.