Years ago when they still had a Western Car wash convention I used to talk to the guy at the Smooth Bore vacuum hose booth every year, he was there every year. In our conversations he told me that you can only get 210 CFM’s up a 2” vacuum hose. He used to laugh when people would come to the smooth bore booth and want to add more motors to the their vacuums. When my vacuums were new I used to get complaints that the hose nozzle would suck the carpet up off the floor of the car. With all that said I would keep what I’ve got now. Keep your vacuum
door gaskets in good condition, clean out you vacuums regularly and you shouldn’t have many problems.