I just did a 2" tank lift on my 15 RGS. I used parts from the hardware store, only cost me $5 and about 10 minutes. I love the look. Now the bottom of the tank lines up with the bottom of the fairing.
(2) 2" U-bolt. I only used the flat bar that is on the u-bolt.
(2) 5/16th x 3/4" hex head bolts
(2) 5/16th self locking nuts with nylon
(4) 5/16th washers.