My head touches the roof with the seat in the lowest possible adjusment (as I am sure many others it does too). Road racing with a helmet on was fun, as I couldn't sit up straight, nor be fully seated in the seat.
I was slouching and "slid down" a bit in the seat just to have my head looking at the road. Made hard cornering fun, hahaha.
Kinda glad I bought a car to turn into a "track only" car now. I can get seat brackets for the SE-R that lower the seat 3/4 inch, and Im ripping the headliner out in two weeks (another 1/2-3/4 inch there)