Stock v. Stock
The manual 5 speed GT's shouldn't have much of a problem vs. Cooper S.
The auto GT's may have a more difficult time, but proper use of the autostick should bring you a hairpin win.
If you do win the race, and someone gives you the excuse their car handles better...... Tell them, "Welcome to America, where the 1/4 mile is king and handling is second." [
] (I'm not advocating street racing, just annoys me when people say their car handles better.)