It depends on the type of paint you are using and type of spray equipment you are using. A HVLP spray gun uses lots of CFM and generally puts down more orange peel, but it can save on paint used. A more conventional gun will require less CFM and will put down a smoother finish, but will use more paint. A good HVLP gun can use 13-15 CFM. So unless you have a huge air compressor, go with a more conventional gun. If you use a HVLP gun with not enough CFM, you will get a horrible finish.