I want to upgrade the system in my Ultra Limited and was going to go with the RF PBR 300x4 amp and Polk MM651's and then get speaker adapters and then a wiring kit.
It looks like Yaffe's Bagger Nation has a whole kit that has the RF amp but uses the RF speakers vs. the Polks. It also already comes with the wiring kit and adapters, instructions as well as having the ability to add the saddlebag speaker lids in the future. It looks like this may be a good way to go.
Does anyone have any info, experience or insight on this set up?

http://www.baggernation.com/products-stereo.htm
The Bagger Nation Ultra “Supreme” 75EX System

 

I would go with your original route. I just did the pbr300x2,mm651 combo and have about $330 in it with adapters and wiring kit. I dont think the mm651 will work with the pbr300x4 as they are 2 ohms and the amp is 4 ohms. So you many need to reconsider the mm651's

 

I have the rf amp and rf power speakers 6.5 in fairing and 6x9 in bags w/sony head unit and am happy with sound it gives.

 

That's why I was thinking this set up from Yaffee. It has everything including speakers for the rear, all RF stuff

 

While the kit would be easier, if you want to you could piece together the same components of the kit for cheaper. While it would not be complete plug n play, you would save a good chunk of $$.

 

What he said !! ^^^ Convenience is NEVER cheap !!!