I used a serrated knife, and a grinder, be very careful with the grinder takes alot off real fast, real light touch. Then I kept putting it on the bike got close, took it for a little romp, sanded a little more, through the cover on. centered it couple staple here and there, just to make sure it looked even then finished the stapling. Done.

Granted if you look at the seat in stock form the stitched seam is at the top edge of the sides, now it tucks almost underneath the side. I had my lepera right by its side the whole time checking the profile for reference. Its just as comfortable as the lepera, although thats not saying much after 6-8 hours in the saddle.

 

In the past, I have used an electric knife to remove the larger and some of the detail pieces of foam. The electric knife allows a real soft touch and very thin pieces to remove. Of course if you are heavy-handed or ham-fisted, you can do quite a bit of damage with it too. A random orbital sander makes the final smooth shape of the foam. Wear goggles and at least a bandana. The foam dust gets everywhere. One last suggestion: go to harbor freight and get the electric stapler ($10 on sale). When you are fastening the cover with staples to the seat pan, it makes for quick, smooth work of attaching the fabric to the plastic seat pan.