What you need is a LOUD guitar. I know you probably have your favorites, but here's my two cents.

A LOUD, percussive, mid-range-toned guitar, even one that sounds like absolute pants in any other setting, would probably do very well on the street. What you need to remember is that playing in front of talking people, honking cars and general noise is no different than playing an acoustic guitar with an amplified band behind you. What needs to come through first is the PRESENCE of the instrument, the brassy, cut-through-the-mix tone. THEN, after people see/hear you, they will stop. A LOT of people wouldn't know good guitar tone anyway, and the point of playing on the street is to make some dough besides loving the music, right?

I have played kids' guitars, student models, that were GREAT for the street, because their tone might have been a bit boxy, but they were LOUD as anything when I played some ragtime-style block-chord strumming.

Find yourself an acoustic that is really loud and has good sustain. Look especially for older import guitars; I have had several Japanese dreadnoughts that were good and loud.

I play exclusively finger-style as well, so I understand the trouble with being heard.

LOSE the amp. I have a friend who lost his spot on a street because his amplified guitar AND mp3 backing tracks were disturbing the local business people.