X15 cummins performance series 485-605 does anyone have experience with these new engine?

Im looking to buy a new international HX520 dump truck with a X15 485 performance series engine and and allison 4700 ofs trans.
These engines are about a year old now and would like some input of them if they are reliable motors or not?
Thanks!

 

Ive had my truck for about 2 weeks now... You'll love the stopping power of the engine brake of the x15 bolted to the rds4500! I barely have to use my brakes. The engine brake cuts of around 17mph so you have to stop it from there.
I have the 485 performance engine and it takes off great and has plenty of power until I hit a bridge around here in sc. Then I'm not to happy with the power. I wish I would've stepped up the power some. But I'm not sure if that would my fuel mileage any or not. I guess you would just have to keep your foot out of it.
I'm averaging about 4.9 mpg right now and using about a 1 - 1.5 gallons of def fluid per 100 miles. I sure hope this gets better with time. I'm about 3100 miles now

 

Yes in not either on the fuel but I guess when I'm cruisin with the cruise control on on a level road empty the truck estimates 7-8 mpg and loaded it estimates 6-7 but 95 % of my driving is around town. I never have more then a 10 mile stretch of open road to put the cruise on without stop and go traffic.
I wasnt given and info on any fuel max 2.0 on the trans. I didn't really ask either.
I have 4.30 rear gears and a demo body. Truck weights in just over 29k full of fuel or just under low on fuel.