I can't seem to find my last post about this topic so I'll try again. I basically understand the purpose to the TC locking up in OD. But B&M sells a kit where you can lock the TC out in 1st, 2nd, 3rd. I think my car had this installed when I first had it, because if in OD and I flipped this switch the car would cut off. But what are the advantages of locking it out in 1st-3rd.

 

The only advantage is that the car may accelerate better W/O L/U applied since you will get torque miltiplication W/O it.