I like to check Ebay occasionally for GL1800 parts to see if I can find a good deal. I found the lower trunk spoiler that way. One day I found a Diamond seat that a guy had purchased, but his wife didn't like it. Besides being a nice seat, it was made to lower the rider 1 1/2 inches and that was the feature that attracted me. I won the auction and got a brand new seat for half the price of a new one.
The seat also includes a rider backrest and the passenger backrest. The covering is velour which is supposed to be cooler. The padding is memory foam.
From reading the Goldwing forums I knew there have been quite a few complaints of the Diamond seat pan not fitting as well as they should. I set the seat in place and found the seat holes were a good 1/2" forward of where they should be. There was no way to scoot the seat back far enough to compensate and if I did there would be a gap up front. I started pondering a solution.
I didn't want to butcher up the stock spacers so I decided to make some spacers out of wood using a 1 3/8" holesaw.
I cut out a notch where the seat bolt will go and used two-sided tape to make the spacer fit snugly in the hole.
With the new spacers the seat easily bolted in place. I like lowered seat. I can touch the ground much easier and I feel like I'm sitting 'in' the bike more. The backrest is larger than my Utopia, and I like the velour. My girlfriend sat on the rear seat and gave it her approval. She said it wraps around more and lets her sit more upright.