Originally Posted by lmccoll

A spragless converter can stand more horsepower, but is not to be driven on the street any at all. If you drive more than 1/2 mile to 1 mile, it will overheat the transmission in a hurry. The sprag is a weak link in the converter. The sprag allows some oil to bypass in the converter and reduces heat a lot. A well built Sprag converter depending on brand and type can be rated as high as around 600 hp. The cheaper (less than $200) converters might handle 400 to 450 hp, a 600 horsepower converter is going to cost twice that usually.

If you are going more than about 600 horsepower, you will need a spragless, but don't drive it down the road and back.