I was wondering if I could upgrade the seats in my 1998 mustang GT to have headrests that actually might do something? Are the headrests removeable and upgradeable or do I have to buy different seats and what other models might fit in this car?

 

Ya any 94-04 seats will work.. Im sure the 05-10 seats will work with very minor modification.. Fab up minor plates or find a safe place to put nuts and bolts through and splice the seat adjuster as needed if at all.

Personally I am a taller person.. I have upgraded to a different headrest style.. and did a quick fab up job with some plates down below to set my seat back an additional 3 or 4" 's.
I love it.