You bet.
http://www.valkyrieforum.com/bbs/index.php/topic,10426.0.htmlFollow the link for the how-to.
I changed out mine for my rear speakers when I had it mounted on my Shadow ACE Tourer. But I didn't really find them better, but then, it wasn't me on the back of the bike.
Also people add in a AMP too. Also on the link. Search will find a lot more for you.