lets not sully a good thread with the 'usual' ... 
nice work TT. some good points , I think stokeballon also mentioned that the side mounts were the biggest culprits too going against the idea of the lower being the primary strain taker. cant visualise in my head why but fact is more proof than theory lol
I can see where peeps are coming from. Yes, the lower rear mount
should be the 'primary taker' of the torque reaction strain - and indeed it is. However, as much as we slag and beef about the OEM lower rear mount, it actually has fairly limited tollerance for movement - even when totally shagged. There is probabaly only about 3-4mm each way (back and forth) in the lower mount - which is what the cheaper options of the poly inserts fill quite well (be they a very poorly engineered solution).
But both the side mounts have about 4 times the amount of play in them. Now, 4 times doesn't sound that much - but think how they are are being acted upon. With the lower rear, it is being acted upon at the very extreme of the engine (the furthest away from any imaginary 'centre pivot') so basically with the lower mount - what you get is what you see. But the two side mounts are probably as close to the 'centre pivot' as possible. Lets for example say there is 16mm movement each way - multiply 16mm by the length of the 'pivot' (so that is from the centre of the side mounts, to say the bottom of the sump) - then you can see why the two side mounts have a far greater effect than many may actually think.
personally i think silicone is a cop out,
Huh - why? Silicone filling of voided engine mounts has long been the de-facto way of stiffening mounts on Group N cars (rallying and circuit racing) which need to keep OEM parts.
when you could have created some dynamic engine mounts ala the new porsche's design 
You lost me there . . .
you plan to post up instructions / proper part no's for others to follow the DIY?
What, for the whole shebang, or just my silicone mods?
Why would I use new mounts as a basis for the mod and not my old 'well used' ones out of interest?
Two reasons - firstly, the silicone really does need at least 2 weeks, ideally 4, to properly cure - you are talking about prolly 3inch thick silicone - and mine were still vinegar stinky after about 6 weeks - so can you prop up your engine on bricks for that long whilst they go off? Secondly, my old engine mounts were well and truely fooooked - when you use silicone, you are actually supplementing the existing rubber in the mounts - so if the existing rubber is past its sell by, then you are only really doing half a job.
Time for kip now . . .
