Look I'm not trying to be pushy argumentative here and I can't disagree that there should be more science involved than "feel". I'm not at all saying that filling the open areas of the mount with polyurethane won't help. I just feel (or hope) that other fellow AccordX enthusiasts who have tried the metal framed mount and said that it has made a difference aren't throwing out smoke and mirrors. It is interesting that Honda discontinued the metal one, but that makes me wonder if that's more of cost cutting or supply chain reason than anything else. I do look forward to see if the polyurethane fill will make a difference though for sure.If that's the case why aren't people with 2.0t auto "upgrading"? Did you test the hardness of the three different mounts on a durometer to determine hardness for what the other 50%of the mount is made from? Did you test the difference in stiffness between the composite and the metal? The person that I know of that put the metal one on the AT said it did nothing. Also have you seen pics of the metal vs composite? Half of the center is missing on the metal mount.
Let me clarify as I was being cautious on my words with the troll afoot. The outer plastic composite portion of the mount is not flexing in a noticable amount period. It's not designed for that. It is a rigid material. If it flexes too much it will snap just like metalr. If the Hasport mount was made of composite it would perform the exact same way. You can make a composite just as rigid as metal and again, if you are approaching the stress limits of this mount in a way that the outer composite or metal is flexing, that car is making serious power. The biggest difference is the composite won't rust.
You make mounts stiffer by one of two ways: increasing the hardness of the mount, or changing from an open mount to a solid one, even keeping the same hardness as the open one. The largest change comes from switching to a solid, and in many cases, non liquid filled mount. Here is a good article for you to read.
A “tunable” motor mount that can change its dampening characteristics has a significant NVH advantage over a passive hydromount or a solid mount.www.tomorrowstechnician.com
Edit: Also as stated above the metal part number according to one website (A21) has been discontinued so not sure if they are going to keep making two different parts anymore or what the deal is there. May have to wait a little until current stock is depleted to find out.