It has been more than a month now that I got Konis "installed" on the Yeller. Ever since they were on the car, the shocks were making a popping noise on rebound, and it was getting louder and louder as time went on. So last week, I took my car to Dietsch Werks, where the owner, Rob, took one of the front shocks out to see what was going on.
This is what we found. The folks who did the original install failed to use all of the hardware provided in the box, as the picture from the Koni manual shows. You see, there is only one nut at the top of the shock, where there should be two: this one and a jam nut, to prevent them from vibrating loose (that's part 5 in the diagram).
Then they also helpfully forgot to put on the little spacer sleeve (3) which goes underneath the top mount bushings to prevent exactly what happened here: too much play in the top mount assembly causing the shaft to slide up and down through the bushing, which also includes a metal washer, which has been rubbing on the threads of the shock and making that popping noise on each upward stroke.
It was doing it so much that the hole in the washer has been worn wider, and kind of oval, from all this rubbing. Thankfully, the washer is made out of aluminium, and has not yet done any visible damage to the threads of the shock.
The top mount bushings for the S2000 (as most any other parts) have to be ordered from Honda, and were on back order last week, so I will have to drive the car in its current state until they get there, as well as the little spacer sleeves from Koni. Once they are all on the car, I intend to take the invoices from this latest round of un-fucking the car to the geniuses who fucked it up in the first place, and hope that they will not make it difficult for me to get the money back.