Ok so help me understand please. If I climb a hill with a slightly "under powered" engine and can only do 40mph compared to 60mph with a "modern" power plant why is this a bad thing? The way I see it is this, as long as you control your RPM when climbing a hill and control your decent on the backside of the hill the only difference when comparing power plants is that one climbs the hill a bit slower than the other given the same set RPM for each engine. Why is this a big issue? I realize that the modern transmissions have hill decent control and things like this, but dang how did we do it back then when we didn't have these luxuries? My 2005 Starwood 28rl weighed about 10k fully loaded and I am sure that there were Dodge 2500 w/ 5.7 hemi trucks pulling these all day long. So as long as the axle ratings are fine, and assuming he has the right rated tires he should be fine. The only thing he gains is getting up the hill a bit faster. IMO