I have the Westach combo EGT/boost gauge in the hole. It works fine. My e-brake is a PacBrake for 35 lb valve springs. It works just fine. The 60 lb model is better, but this one does the job. I can go from Eureka, CA to Redding, CA pulling my 7500 lb travel trailer without using the service brakes except for traffic. There is some very steep crooked places on that road. One of these days when I get aroundtoit I will replace my valve springs and upgrade the PacBrake.