So, right now I have a Sony HU and Biketronics 7.1's in the fairing (these both stay) i am using a RF PBR 300x2 right now. I am adding lower fairings and want to add some 6.5's down there and power all with a SS4.520. I DO NOT want to add a second amp under the fairing, i want to do it with a single amp.
Now for the questions:
1) the SS is a bit bigger than the pbr300x2 but I don't forsee any mounting issues by stacking atop the HU, correct?
2) The SS is 2ohm stable but my 7.1's in the fairing are 4ohm. Does this limit my lower fairing choices to 4ohm only or can I mix and match so to speak?
3) Lower speaker choice. I think the obvious choice would be Biketronics 6.5's but I really do not want to fork out that much coin on speakers especially where these are placed I see them as a "supporting cast" to the main fairing speakers. I have been looking at Kicker DSC654's if I have to stick with 4ohms...thoughts?

 

1. It will fit. Mine was a little tight on the sides. I just loosened up the wiring harnesses on the fairing supports.

2. You can use 2 ohm speakers if you want.

3. Speaker choice is subjective. I think Biketronics gives a lower price in the 6.5's if you tell them you don't need the adaptors. Might still be more than you want to spend, but it would help a little.