I’m thinking of fitting Dave Slacks front disc kit to my bus using the stock master cylinder. I’ve heard that if using the std MS you need to remove the non return valves . The person who owned my bus before me had Porsche 944 discs all round and was using the same master cylinder. I asked him if he had removed the valves but he didn’t know as he didn’t fit them himself,but said he never had an issue with brake binding . Would that indicate they have probably been removed?