Will a KNS adjustable Piston for an AK fit a Galil ARM? Every video I've seen is how to fit one to an ACE. My Galil tosses the fired brass at 2 o'clock and into next week for distance.

I'd like to tone that down, plus I'd like to run this suppressed.

What are my options?

yes, get the galil specific one.  this is the one I got.
AGP A 18

My JRA ARM Gallant used to toss them into the next county till I put an ALG extra power AK recoil spring in it. Smoothed out the recoil a lil bit too...... not that there was any to speak of to begin with.  I'd toss a spring in before coughing up $$ for the piston. Ya' know that recoil spring has probably been in there since the gun was new, a LONG time and a lot of rounds ago.