Car audio upgrade suggestions needed?

[mrkleen340]

I have been thinking about upgrading my car's sound system. I want the bass to pound but I'd rather not be that guy you hear from a mile off. In other words I I want a system the people in the car can feel and tell isn't stock, but those around aren't disturbed too much. The car is a 2004 glx passat already with a "monsoon" stereo in it.

So anyone have any suggestions as to a configuration of subs, amps, ways to not get scammed at the audio shop?

Thanks for any help, and no I don't know much about car audio.