fastback66inAus
 

I'm looking into getting a '66 fastback. They seem rare enough in Aus which is good cos too much of the same isn't really that good, but more mustangs on the road in Aus is a good thing.
I'm not really sure of what can be done to one, nothing too drastic though.
Any ideas???????

I think everyone would agree that the best performance improvement is changing the rear end gear. Most early mustangs came with 2.80 open rear ends and huge gains in performance can be made by increasing the rear end gear. I have a C4 automatic so I swapped to 3.55 limited slip rear end and it is great. If you get a 4 speed or car someone swapped an AOD into then go for steeper gears, 4.11 is about as radical as most street driven cars go. Good luck finding a mustang and have fun with it!
-JON