I just did this mod today on my 08 as I'm sick of my arse being in pain from the seat. It's not so much from the canyons as it is when I need to slab it on the way home - major saddle soreness.
It's not a difficult task and it took me about 2 hours start to finish, including having to go pick up a staple gun from the local hardware store. I used a "Powershot 5700" staple gun (pic 1) and I recommend you stay away from using this particular gun. I don't know if I need to figure out a secret technique for it but the staples don't go in well and I had to re-do a few and/or try to squeeze them down with a plier since many only inserted about halfway. This extended the time for this job considerably and I would've been done sooner had I had a better staple gun. Also, I used 1/4 inch staples.
I'm not sure how the cover will hold up from the foam being more "squishy" but from the other posts, it seems that it isn't an issue. I can't wait to test it out properly.
Hi headshake1 I've also done my R1 07 seat as you have, but went one step further and added a thinnish layer of foam over the top of the seat pad to make it more comfortable. I have a mint spare black seat that I picked up off Ebay very cheaply so didn't have much to lose, but my variation on a theme seems to have worked out ok.
Variation on headshake1's method:
The twin layer foam I used was a camping mat I had doing nothing and they are available very cheaply from stores or Ebay, as shown in the 1st picture, it's 5/16 inch (7.5mm) thick. I removed the seat pad carefully from its frame and cut the unwanted foam out from the underneath of the seat pad which can be seen below in the 2nd picture that shows the depth of cut. I also glued a piece of foam between the seat frame and pad. I then glued the seat pad back into its frame using contact adhesive in a few areas so it stayed put and didn't move around.
I then cut the foam out large enough to cover the seat pad and run a line of contact adhesive done the middle of the seat pad and the foam, but just short of the ends, you'll see why further on, see picture 3. I then waited until the contact adhesive was dry and ready to be pressed together. Then started to stick the foam onto the seat pad in the middle working towards each end to exactly follow the contours of the seat pad. Do the same with the front each side pulling down on the foam before you stick it in place it is stretchy and easily manipulated, again don't glue up to the edges as you will need to glue the edges down last.
Before you do the same to the back I thought I'd try to keep it standard and make a 'V' shaped cut out in the foam as per the original. Now you must use the contact adhesive again to stick the back half of the foam down, again avoiding the edges but not over the back of the seat pad sides as shown in picture 4 as it'll be difficult shaping around the back side edges unless you cut the foam. Now the foam is stuck to the seat pad you can now apply the contact adhesive all around the edges, wait until it goes off and stick the edges down.
You now need to trim the foam edges up to match the contours of the seat pad edges, but avoid going over the front edge of the seat pad as shown in picture 4 as you'll hit problems with tank clearance. I used a sharp pair of scissors, you could also use a Dremel or a craft knife. Take your time blending the foam into the contours of the seat pad, this is very important or you could have lumps and bumps showing through the seat cover once fitted.
Once the foam is blended and contoured correctly you can replace the seat cover for a trial fit. Don't
miss this step as you might find that more of the foam needs trimming from the seat pad. Once your happy with the shape and fit you can now fix the seat cover back on with a heavy duty staple gun and 1/4 inch (6mm) staples.
Fitting the cover back on is a pain in the a$$ of a job just as the seat was before this modification!! This is because of the added thickness it can be difficult to pull the cover where you want it, but gentle use of a heat gun on the cover can help. I worked from the back of the seat pad where I'd already left the staples in to the front first pulling the cover as tight as you can between the two points to get a good fit around the sides. The sides were done starting at the rear of the seat pad.
Picture 5 and 6 shows a front and rear view of the newly modded seat and an original seat, the original is on the right in both pictures, as you can see by it's thinner profile!!
I hope this helps a few fellow R1 07/08 riders out, even though I'm yet to try the seat on on the road as the weather in the UK is crap at the moment! Sitting on the bike with the seat fitted you can feel it doesn't push you into the tank as much, and the seat feels more padded and comfortable.
I can't wait to try it out on the road and will post back once I do.