Liquid urethane mate. Silicon would just squeeze out. You can buy it on ebay with different shore durometer ratings. Aftermarket mount makers often put the OEM mounts at 40 shore, so I would get a urethane of similar rating, or a bit softer.
You basically get some good OEM mounts (preferably brand new ones), glue a piece of thin wood or plastic to one side, or silicon it on. Then pour in the liquid urethane at the open end so it fills up the gaps. There are plenty of videos on youtube about it
That is pretty much what the 034 Motorsport street density mounts are, but they're not cheap! Redesigned rubber mounts without the voids.
All 3 Vibratechnics mounts WILL increase noise and vibrations, just to make that clear. Just to a lesser degree than poly mounts. It's the Vibra dogbone + OEMS that give near factory refinement.
Cheers for the info Pudding, very informative. I'll look into this when I get round to my little chassis overhaul. At the moment the plan is KW V1, Superpro ALK, and mounts. Maybe H&R roll bars too. I'm prepared for the increased stiffness and vibration. It's kind of inevitable I'll lose a fair degree of comfort depending how far I take things but that's the price we pay.
Here is a good thread for DIY engine mounts -
http://www.superhonda.com/forum/f94/diy-homemade-polyurethane-engine-mounts-204274/That guy used 60A Durometer urethane which is a tad bit stiff and said he gets vibrations at idle. I thought our mounts had some voids in them, jesus, THEY are voids!!!
Liking your plans! Don't get me wrong about the VibraTech mounts (as in all 3, fast road spec), they really do tighten the car up round corners, and the vibration is less during summer, and only at certain rpms.....but it is there, and it is irritating. I had them on my MK4 R32 (now THAT is a big lump to keep still) and they worked great, but caused a horrible shake in the cabin at 1200rpm. An rpm I used frequently on a daily basis, so they had to go. I went back to OEM with a dogbone. The MK5 would be the same. Same mounts. I need to find a middle ground! Maybe the 034 motorsports option?
I have acquired all the bits to switch over to alloy hubs and wishbones, and the VWR spring/damper kit is sitting at home awaiting fitment also.
I need to get it done ASAP. Followed a Corsa VXR the other night at some fairly fruity speeds on a back road. Left handers, fine, but on a very sharp right hander, the VXR shot round with no drama. Mine practically understeered off the road, and it was dry! Fair enough, summer tyres (PS4) and 2.5 degrees, but he was on summers as well
I'm just hoping it's a combination of a heavier car and 107K old suspension....and my missus adding weight to that corner
If a Corsa can outhandle a MK5 GTI, then I'm hanging up my modding gloves forever!!