What year GT500 for open track events?

[sl0214smith]

I want to buy a GT500 vert for weekend use and a few open track events a year (I am aware of the downsides of tracking any convertible). At track events I don’t want to be the fastest car, just fast enough on the straights to pass the small cars that passed me on the corners (I have some track experience already). What are the advantages/disadvantages of the different model years of GT500’s? I am particularly interested in systems that can or cannot be disabled.