Nothing to do with a c15, but i put a chip in my grandpa's rv with the c9 acert. Made a huge difference over stock in pulling steep hills while he is traveling, with about 1.5 - 2 mpg better
I just looked at PDI but damn the prices are crazy, but then again i am only comparing to what we do with our trucks and EFILIVE.
Price a bullydog module for the c-15....lol. pdi is essentially efi live for the big boys, my boss used to have a pdi tuned MXS (acert) that got 6 mpg pulling 105,000
I don't, I can ask him though.