<font color=blue>smknchk</font color=blue>,from your profile picture I can't really tell how tall you are but it appears you have a small athletic type build. I'm about 6' and weigh in just under 140lbs and I ride with the Dainese Backspace 2 protector. Dainese offers 3 sizes to fit individuals of different heights; I believe the Backspace 1 is the smallest offered (I have the info at home in an email I believe).
Most any back protector will work just fine I think, it just comes down to comfort, style, etc. I usually wear the Impact Armor protector combo for track days, but I have a Knox protector that's good as well, although it doesn't have a chest protection unit. I used to wear an Alpinestar turtle-style one, and that was good too. See, they're all good