Another converter says Cummins 5.9 super slow?

[Clay_in_Florida]

Been lurking here for years, my first post

First off, always been a fan of Cummins 5.9L. Been running them for years in trucks for towing and always seem to have torque for miles. I was thinking of looking for that engine in my conversion because I am comfortable tooling on them.

So to the question. On the vlog here: https://youtu.be/Egg0VkIclec?t=5m48s

It sounds like the main reason he is selling his bus is because it is slow as hell. He is claiming it is topping out at 50mph on the flat, and dropping on grades. Maybe with or without a Wrangler toad. Blames it on being a city bus. I think he has a allison 5/6 speed. Does this sound right, or does he have engine trouble?

If it is, I think I will cross this motor off my list.