You want to be careful and not exceed the pressure rating of the old tanks. Most single-stage compressors only run up to 150 PSI and have a lower max pressure rating and pop-off valves that trip before 175 PSI, and twin-stage usually go up to 175. I have two compressors tee'd together, one of which is higher pressure than the other, but I set the switch on the larger one to come on only a couple PSI before the smaller one, and the shut-off pressure the same as the smaller one. The compressor definitely cycles much less, and in my opinion the starting/stopping of the motors wears them out faster than running. The compressor used to come on twice during a top auto wash cycle, now there are occasional times it doesn't need to come on at all.