My car is street driven and I am using a non-lock converter. Here is how I see it. You are already running 4.10's so your gas milage is going to suffer and that is the purpose of the lock-up feature anyway, increased gas milage. What difference is the extra 200-300 rpm going to make that the non-lock will cause? As a bonus, you get torque multiplication in 3rd and less stress on the input shaft when it shifts into 3rd. Im sure you will be running an aux trans cooler so the heat shouldnt be too much of an issue and you can get non-lock converters that will work with the 2pc input shaft so having to pay for the change to a 1pc is not totally necessary. Just my opinion.