I am getting ready to start finish welding a chopped 49' Ford I am working on. The sheetmetal is 18 gauge and I am burning through with my mig. I am considering purchasing a tig to weld the sheetmetal with and to also weld some aluminum frames for my motorcycle. I see the Dynasty 200 goes down to 1 amp output and the sync200 goes down to 5 amps. What amperage is ideal for thin gauge? Which machine would you suggest? Money is always a consideration and this is a hobby.