A 16 ga stainless or thinner lap joint can be a bit tricky because while you want a certain level of penetration, you don't want to burn thru.
Stainless steel requires less amperage than carbon steel but that doesn't mean it should be welded cold and slow.
Get your puddle established and moving within 3 seconds...2 seconds is even better.
this will prevent a build up of heat that is difficult to out run.
I used .056" thick 304L stainless and 47 amps with a ceramic jazzy 10 cup and 25 cfh argon...along with .045" er308L filler rod for this lap joint.