Exhaust Temps

Need Help, Have 2011 GMC 2500 4X4 with LML, have temp monitoring system, it is the new Gauge Tuner (Bullydog) Keep it on stock unless towing, will be driving and fuel mileage will drop from average 16 to average 10 in minutes and Pyro1 will go from 550 average to 700 average and Pyro2 will go from 550 average to 1100 average, will do this couple of days and then go back to normal, has anyone had this problem or know what it is?

Sounds like a typical regeneration cycle for the DPF.

So there's nothing to worry about, I never noticed this until I put the GT on it because I couldn't monitor temps. Thanks