I just want to add to the J&M comments.
I have a '09 SERG O/B. I bought the J&M 7.25" speaker upgrade kit, around $220, can't remember for sure. I did not want to get involved in the amp issues, just the KISS system for me.
I could hear my original speakers at lower speeds, but even then the quality was not all that great.
I installed the 7.25" J&M speakers with their adapters and under fairing sould insulation. The intall was straight forward.
I'll have to say that for the couple hundred bucks and an hour of work, it's one of the best upgrades I've made.
Don't get me wrong, an amp would make it better, but for me the sound is a great improvement of the stock '09 SERG speakers. I can hear the music very well at 80 mph and on the talk radio station I listen to while going back and forth to work for traffic reports, I can clearly hear them talking without having to guess what they're saying.
I know there are many other system companies out there to choose from, but at the time J&M was highly recommended. I "still" recommend them for my application.
The choice is always yours.
Good luck with your choice for speaker upgrades.