I want to reposition my home port decal but when I removed the decal I noticed some difference in gel color ( yellowing ). I tried to buff with some leverage but is still noticible. Will wet sanding make a difference or will the discoloring still be noticed?

its imbedded in te gel so most likely its stained..try the fountain of youth product..power one

http://vimeo.com/16328432

The difference is from UV rays breaking down the outer layers of gel at different levels. Sometimes you can polish it out, sometimes you have to compound, sometimes wetsand, sometimes nothing helps. Work from the least aggressive to the most agressive and you may be able to work it out. Ive never used Leverage so I couldnt tell you how much cut it has in comparision to other products.

Any recommendation on another compound to try next?

Aqua Buff 2000 or Aqua Buff 1000. If that doesnt take it out, time for sanding.