I would put fuel system upgrade at the top of your list, first. Guages, #2. Lots guys have ran the comp box with no gauges and tow. I don't aggree with that and yes you can damage your engine. If you do tow, keep your rpm's above the 2000rpm and keep the turbo spooled up. Honestly, your taking chances doing it. I don't use my gauges to control when I take my foot out of it but thats me. My truck can't tow with my current set-up as the injectors are to large. I towed a 8k trailer with a comp box and 90rwhp injectors. Yes she got hot once or dozen times. Sometimes passing I would exceed 1500deg's. Now I hardly see above 1500deg's. My truck looked good inside when I took it apart. I was supprised how good everthing inside but the cummins is a pretty tuff motor but not indestructable.