will my propshaft rubbers break and leave me stranded on the bypass with cars going past at 70 mph thinking "F-reg, shouldnt that thing have been scrapped ages ago, why does it have racing seats in it?"

My engine moves about a lot and its opened up the exhaust joint between the down pipe and front pipe.

Quite the opposite i'd say. I broke my prop with properly knackered engine mounts, now i've got new Poly ones fitted it feels a lot nicer. The revs don't sound as "jumpy" over bumps in the road and it just generally feels tighter than it did, hardly suprising though as they were kippered.

I think I know what you mean, my engine wants out! I was concerned that good front mounts and old bellhousing mounts might put the alignment to the gearbox out and stress things.

im fitting solid mounts this week, will report back with progress!

Solid mounts with stock engine = bum ache.
Solid mounts with valver likely to equal engine breaking free.

Mr SC, I've just made an aligny thingy for my engine and prop out of my busted propshaft and a laser pointer, just try and do something to check they are in line before you bolt up, once set it will be much better.

just be careful about the mounts on the engine side i fitted some range rover body mounts and after a while (hard hard abuse)
it snapped them so just summet to be careful off

The idea of the poly mounts is to reduce the stress on the prop. A lot of props fail due to soggy mounts.

The only problem I have ever had with prop is the torque sliding the prop off the splines!