Unless we hear from the horse's mouth, I'm leaning towards extruded. Neither their website nor catalog in the past 3-4 years I've been following them mention their S7 base as sintered. If it were some form of sintered, why wouldn't they just say it and keep us from speculating? Blisterreivew has been stating the S7 base as sintered in the their past several amrada reviews, but again, I'd like some sort of confirmation.
With that said, I still picked up a pair of 18/19 96ti zeros. Granted I took good care of waxing em from the start (2 rounds of base prep waxing before they saw snow and waxed every 3-4 ski days thereafter), and can't say I ever noticed them being slow. I remember once bombing whatever the groomed trail is from top to bottom of 7th heaven at Whistler and wasn't disappointed by any means.
However I am a bit disappointed in the durability. It felt like every day I took them out, they ended up with some noticeable dinger(s) to the base that I'd have to ptex about half of. My other skis are BC Atris that have prob seen 50+ days and light scratches are about the worst damage I've seen.
FWIW, these have solid black bases along the whole contact length. I've never had Armadas with non-solid black S7 bases, but I'm still looking pretty hard at a pair of arv 106s.