Got the 4in extensions in this morning, have to say it took a lot longer cleaning up the finger prints than it did putting them in
He's right with moving the mounts back from the templates they give you. I gave myself about 1in spacing between the bar and the seat. Then had a bracket fabricated that mounts to the bar and attaches to the top bolt of the seat. I figured out that the taller the bar is, the more weight that's at the tip of the bar. Made it easy for the bar to move around and smack the back of the seat while riding. So had the bracket made.
yeah mines the 25, the bend at the top with the point actually has some weight to it. Probably would of been fine if it was straight. But the bracket i had made has the same diamond shape that on the back of the seat. so matches pretty darn good.My sissy bar is 20" old school hard core and no problem with vibration when riding and as far as I know there is no problem with the 25" version either, however there is no bend at the top with the style I have so less mass to move around. Better to be on the safe side though and add some reinforcing.