My Harbor Freight is the cheapest flux core 120v. With the little flip high low button. Cost $200.
No fine tuning there except for speed nob and how fast or slow you move.
It barely does exhaust. Plus it gets hot fast.
It will penetrate on the high setting, but don't expect anything pretty, and you get spatter everywhere. Pin holes to go back and re hit galor, no mater how smooth you weld
Farm tractor or beater exhaust. Gets the job done. Yes.
But I would be ashamed to weld a paying customers exhaust with it.
If could do it again, I would have got a used Miller or Lincoln . Or even even a new Craftsman or Century. With the option for Mig.
However the auto tint welding hoods, and other accessories they have, work quite satisfactor.
My brother just bought at Lowes, ordered on line and picked up. A nice little 120v Lincoln Flux and Mig about $400. Came with a regulator.
He loves it. It welds way better then mine with flux, and lays perfect virtually spatter free, welds, nice little dimes, with gas added.