I'm looking for some advice on the best tool to use for grinding/smoothing out stainless steel welds on exhausts and manifolds, typically on the joins between sections internally. Up to this point I've been using a dremel with an Aluminium Oxide stone (orange coloured) but I'm wondering if there is anything that could make lighter work out of it?

I also have a decent compressor with a small die grinder and couple of drills etc, the main problem is the correct abbrasive though I think as the stones are destroyed in quick order compared to the actual metal material removed making tedious work!

flappy disc on a grinder