The muffler is chrome plated steel, not stainless, so you can use them anyway.
Most of the metal cleaners have pumice and an oxide remover in them, along with a mess of waxes and oils for consistency and stability control. Most of them contain an ammonia-like chemical, for pH and the fact that oxides are reduced with -OH moieties. Most metals make oxides which are relatively easy to remove. All the cleaners call for rubbing out the blemishes once applied.If a product says safe for use on chrome, does that also mean it's safe for use on stainless steel?
I know the stock pipe on the Honda CTX700 is stainless steel, but I haven't seen any cleaning products specifically say safe for use on stainless steel. They always say chrome.