At 350 hp, would you be able to tell? 10 hp is down in the "white noise". Unless there's a significant difference in the torque/rpm curve, I doubt you'd be able to notice a difference. Bear in mind, I'm a gasser guy and all I know about diesels is from driving city buses at less than 35 mph..
I do know that a lot of the inter-city double-deckers in the UK have 650 cubic inch diesels that have max rpm levels around 2500. Must be torque they value most. It's quite a surprise to be doing the 70 limit on the freeway and be passed by a a big box (14' tall, 8'6" wide and 40' long) doing better than 80 mph. When I was testing motorcycles back there, the turbulence in the slipstream of those things was definitely an issue.
Frank and Eileen
No longer RVers or FR owners