The grey plate is a colour overlay. Made in Photoshop, thats most likely why it doesn't work in GIMP. i will try and fix it so there are no blending options on it for GIMP users.
Attached file contains both CD FZR #15 and #28 skins.
Notice: these skins are private and shouldn't be used by anyone not being a member of the ConeDodgers Racing Team.
IGTC offcials and members of other teams involved in the IGTC league are allowed to use these skins for renders but not for driving online on any server.