Diesel more sluggish than gas?

Our 40' Dynasty had a 300HP Cummins and I thought it to be underpowered. It was sluggish off the line and when trying to pass slow moving trucks. Like Mark said, once the speed falls off, it takes awhile to get it back to speed. The Exec has a chipped ISM which comes in at 525HP and it does make a big difference. Our coach weighs in at 49,500 pounds and while it won't give you a 'push you back in the seat' feel when you leave the light, it's much easier to get moving. The other thing to realize is pulling up large hills. The Eisenhower tunnel is at 12,000' elevation. Pulling up that grade, my coach rarely got out of fifth gear and I held it close to 55mph all the way. You'll find the diesels are much heavier coaches and will be easier and more fun to drive especially in high windy conditions. The tag and air suspensions are huge pluses...there's an old saying, "Don't drive a diesel unless you're ready to buy one"....Dennis