I have been using a Banks TC for around 30k miles. It seems to be holding up well to 600ish hp, towing 14k around town twice a week, and a few 1000 mile trips (towing 14k) a year.
It is priced similar to other brand name converters so its not like you will be spending more on it.
Suncoast or Precision would be another option.
Tell him to get a PHP chip instead of the TransCommand<-----------
.