Source for gel pad - I got mine at Wanner Associates for about $50 including a quarter - inch foam pad. You need to put a pad over it as the gel can absorb a lot of heat in the sun. Wanner is at 717-859-5699. They sell the dry polymer pad that was developed for the medical industry to prevent bedsores with bedridden patients.

Here’s Marty’s instructions that I followed:

"Basically, there are two musts that one needs to keep in mind. First, and most important is the 90 degree angle which has to be cut out at the rear. The stock seat has a gradual slope (putting maximum pressure right at the tail bone) to the bead at the rear of the seat. this should be the starting point from which to cut vertically downward through the foam to the supporting frame. It should follow the contour of the rear of the seat (and one’s butt); tapering to a shallower depth as one comes out towards the sides of the seat (in a curved line following the natural contour of the rear of the seat at just in front of the junction with the top of the rear). Then a horizontal cut should be made to remove the foam in such a manner as to merge with the vertical cut.

"The second most important "must" is that the horizontal part of the seat has to be slightly concave. Your ass is convex; therefore, in order to keep the pressure evenly distributed, the end resulting foam contour must be concave (yes, that means removing even more foam - don’t worry about it). I stress this because there are very few stock or aftermarket seats which are concave. Corbin is an exception in that they have a concave shape; but they do not compensate for the vertical junction between the butt and the back of the tail bone, or spine.

"There is another consideration when seemingly hacking all of this foam out of the seat (scary sounding procedure - but look at it this way, you certainly can’t live with the stock seat the way it is, can you?). Many riders suffer from "crotch anesthesia" after logging a few miles on board. What really helps this from occurring is, when doing that horizontal concave contouring; extend that concavity forward enough to include the area directly behind the scrotum. The pressure on the arteries directly behind the scrotum is what stops the circulation in the whole crotch area, thereby causing "numbness (or lack of circulation).

"At no time during this foam removal procedure should the foam on the borders (or sides) of the seat be touched. The shape of this "cutout" should be dictated by the shape of the gel pack which is going to be placed inside of your cutout. This means that your first job is acquiring a gel pack which is slightly smaller than the top of the seat, before you start cutting. There are two kinds: one is a "gel pack" and was designed for chronically bedridden patients to make them the most comfortable and to reduce "bed sores". The second kind is made of the same material which contours to differing pressures such as the "flow" material in ski boots (for instance). I know of one outfit which sells this in the form of ½" thick seat pads and this is what I would recommend for maximum comfort. The only problem is I don’t know, off hand, who, what, or where to send you to get it. I had a one man vendor (in a small trailer) put one of these lesser known pads in my Gold Wing, and it was unbelievably comfortable (I had it done at Americade last year - the vendor is at all of the major rally’s).

"Using your gel pad as a template, mark the foam with a felt marking pen around the periphery of the gel pack. This will be the borders where you will remove the foam as described above. Keep in mind that the rear of the pad has to end at the vertical cut towards the rear of the seat. After you have removed the foam (it doesn’t have to be very even) from the inside area , following the contours (described above) to a depth of at least ½" (or the thickness of the gel pad). The gel pad should fit inside your cutout with none showing above the edges, and following the concave contours already described. The rear of the pad should fit to the vertical foam cut and not bend up at the rear. Take it to a boat or custom upholstery shop and have them put a ½" foam over all of your work including the edges of your cutout. The reason for this is so the seat won’t retain heat when left out in the sun for awhile. From what I understand, these gel pads retain heat like you wouldn’t believe. Pick out a textured upholstery that you like (black and looking like Corbin’s stock vinyl is what I picked). Then give the instructions to put a crease at the bottom of that 90 degree junction at the rear of the seat which will permanently stay. The way a good upholsterer will do this is by drilling holes in the seat frame corresponding to the bottom of that crease. He will then sew a heavy nylon string from the seat cover all the way to to the underside of the seat through the drilled holes and then tie it there. When done, with beading on the periphery, it looks really trick.

"Contrary to popular opinion, a "soft" seat is not comfortable. It merely allows for any pressure points to go unnoticed for a few miles further before "butt fatigue" sets in. Soft foam seats also allow excessive pressure at unwanted points such as those arteries behind the scrotum. I have found that firmer, correctly contoured seats are more comfortable all day long day after day. Don’t look for softness. Look instead for a firm equalization of pressure for extended comfort.

"One last thing: The idea of getting an impression of one’s butt is assuming that copying that contour will give the ultimate comfort. If that were the case, then the contour of the stock seat would be quite comfortable. The reason why it isn’t is because of the internal hard and soft parts inside one’s Gluteus Maximus. Even though there are really no 90 degree contours in one’s ass, due to the tailbone pressure in that particular area; that angle is very necessary to not get a case of the dreaded "tail bone bite" which can make even sitting in an easy chair miserable for a couple of days after discovering it during a long day’s ride on the Valk."

"To get a better impression of what that "wraparound" 90 degree junction at the back of the Valk seat should look like; take a look at any 1500 Gold Wing seat and you will see a taller version of that 90 degree junction. The only thing to keep in mind is that there is NO upswing contour from the flat horizontal to the 90 degree vertical where your tail bone sits. When you have the appropriate sized gel pack (the large one is correct as the OEM Valk seat really is quite large); take the seat cover off the Valk seat, center the pad on the seat, and you will immediately see where to start marking the rearmost cutout for that 90 degree vertical. This will be the most important place to start. The stock seat is "bordered", or "framed" by ~3" foam borders. These should be left intact so as to retain the stock shape and support at the peripheries. It’s really pretty hard to make a mistake after looking at it as long as you keep these two most important ideas in mind - the 90* junction and the seat concavity. I carved out the OEM foam at the centerline in the rear all the way down to the plastic frame in order to create that concavity as well as make enough room for the gel pad to fit inside of the peripheral borders of the stock foam . Don’t worry about doing this as it’s needed to get the correct contour and you will never feel it through the gel pad and subsequent ½" light foam insulating cover over the gel pad. You will only feel it in the finished product if you haven’t removed enough foam right where your tailbone sits."