The Transom Pad was a total bust -- it tore almost immediately and I ended up scratching the transom anyway. In the end, I attached a large square of teak (8" x 10" x 2") with two large bolts to put the 6 hp kicker on.
I think with a 9.9 you'll need to attach either a Garelick type motor bracket or a larger piece of teak with four bolts -- or just get used to the idea that the Gel Coat will get scratched.
If there is room, you can attach a piece of starboard to protect the transom. Seems most folks use the Garelick type bracket.
Good luck! Let us know what you decided.
Matt