Many in our area, including me, have found the mild steel muffler from Healey Surgeons the best way to go. They have a good sound, are a quality product, and are not made in China. You will never regret going with the mild steel muffler from Healey Surgeons.
My take is stainless is not worth the extra money on a Healey. You'll bash your muffler to smithereens before it rusts out (unless you're using your Healey for convenience store runs).