i wouldn't be concerned with being embarassed. You should be able to keep up with the non tubro 911s and all their boxters will be belong to you. My uncle has 5 porches (2 he drives, the suv and a 911) and 3 he restores/sells. Just from the seat of the pants, the regular 911 doesnt feel much faster than my stock 07 STi.
The turbos and GT3, of course, will be quite out of reach. Granted they cost 150k and 200k respectively.
Really, just enjoy being out there on the track with your car!