The reason for this is because they dont need them. You know that DFC port? And the VAD??? These are two Mares patents and are engineering designs that help with the airflow. Mares regs breath almost as nice as alot of the adjustable second stages out their tuned all the way out. Key word is almost. The dynamic flow control and the vortex assisted design allow the proton ice and the abyss to breath very nice. They dont need an adjustment. Mares actually doesnt believe in adjustments. They design ther first stages and the port positioning and also the little bypass tube to give you the best flow possible. Its actually pretty cool design. The ice is a very nice second stage, much like the abyss, metal housing, just a little smaller and a new design. The exhaust tee looks a little strange though... In any case, I think I would still choose the Abyss... Think about this for a minute: a Mares overhaul (just one 1st stg, and one 2nd stg) will cost you more for parts than a Poseidon now (distributed by Viking now). Thats expensive. And only a two year warranty. Apeks gives you a lifetime warranty with free service kits every other year (recommended service interval). But, then again, thats only if you buy from an AUTHORIZED DEALER. Not on the internet. Lets not start another LDS vs. online thread though.... Just pointing out the diffferences in warranties fellas...