saddlebag sound system

Iv been tossing around the idea of a sound system in my saddle bags for a while now, and it seems like a good idea. The system will mostly be used while the bike is stationary and at low speeds (IE. hanging around carparks with mates, outside local gigs, cruising with mates etc...) Im not after anything amazing, just loud and clear, with decent bass. There wont be much room to work with as i ride a Yamaha virago 250. I am yet to purchase saddlebags, but they will be leather. I am unsure what speakers/woofer to go with, has anyone had experience with the cheap 4" bass tubes that always seem to come up on ebay? I was hoping that one on each side might provide what i was looking for, but at only 4" they might not be loud enough.I have seen people on youtube putting 6x9's and 10" subs and other equipment into the storage compartment under the seats on scooters. This lead me to think that boxing a 6x9 in each side and running them off a "Mini" amp like the one below, for each speaker, might work.Those amps, are rated at 75w RMS x2 Channels. Could i use one each to run each 6x9 at 150w RMS.Finaly, does anyone have any other ideas on what i could do.Im still planning this project so im open to all ideas, but i want to keep it contained in the saddle bags. This will also make it easier for me to remove it when its not needed.Thanks

just go with the 6x9s  face them into the inside of the wheel, they sound louder that way.installers do it best. we got the magic hands!