Here is more detail. I spent a fair amount of time deciding on which components to upgrade my stereo system on the F6B. My Valkyrie rocks and I wanted as good or better on the F6B. The sound system on the F6B is not actually all that bad stock. After 2006, Honda upgraded the audio in the Gold Wing line with more power and larger component speakers. Getting on my F6B after riding my Valkyrie though, it was pretty obvious where some upgrades were going to come. My reasons for upgrading the audio have as much to do with pure fun as it does with necessity .

The speaker in the F6B and Gold Wing line are an odd size. I wanted to put 6.5" speaker in, but didn't think they would fit so I chose a set of 5.25" component speakers. Since then, others have been successful in installing 6.5" speakers by trimming down the frame on the speakers to make them fit. I may or may not upgrade to 6.5" in the future, but I'm pretty content at the moment. Well, my wallet is pretty content. After reading reviews, and scanning many specifications , I chose the Polk Audio MM series 5.25" components. http://www.sonicelectronix.com/item_...io-MM5251.html
We got them for $189 on Amazon. Birthday present. There is a theme here. Wait for it.

Here are the speakers.
I chose these speakers for their low frequency extension. They are rated down to 50 hz. I also chose them because of their reviews and their 2.7 ohm impedance.
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Here is a comparison of the woofers.
Stock speaker on the right.

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The 5.25" speakers are not a bolt on fit. They required some adaptation. I accomplished this with the use of some flat pieces of ABS plastic that I cut into shape as adapter plates.

Here is one of the speakers mounted.

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I have to split this up as there is a limit on photos per post.