Anyone chip a Cummins ISB 6.7 XT?

There are tuners - some are better than others.
Choose one that doesn't raise rail pressure beyond Bosch limits.

Just remember that anytime you increase HP you will create more heat. For short pulls it might be ok,but for a long pull at full throttle could lead to engine damage.There is no free lunch.

So! you're saying he should watch the temp gauge. 1st go to the Cummins engine forums and also read up on Edge Computer. Make sure you get a good EGT readout and run the temps the manufacturer recommends, depending on where you put the probe it can be 1450 degrees for 5 minutes. We have used one for 10 years and love it. Some you can adjust on the fly so if you are pulling La Veta Pass which is 6% and 45 miles you could turn it down so it runs cooler. Mine paid for itself by raising our fuel mileage by .8/gal.

Be sure to check to see that you don't exceed transmission limits.