It would be nice to get a real powerful engine IF so desired, but it does not work that way in the real life. Companies that manufacture coaches install engines according to the weight of the vehicle. If a motor home is around 19K in weight they will install a ISB Cummins engine. I can guarantee you that you will not get a ISL 450 on a light weight motor home. ISL Cummins engines are installed on coaches over 30K lbs.
And you will not see a 600 hp Cummins on a 30K lb coach. It ain't going to happen.
Some people want to drive 80 mph on a coach and that is why they want horse power. Which is crazy.
What a person wants on a coach is torque at the wheel.