oooh, sorry guys :embarassed:, been out this afternoon. I didn't know that there would be so many questions. Topher has answered most of your questions anyway.
Aftermarket torque inserts are enough for most people and these do have uprated tensile strength bolts.
Typical makes are Neuspeed, APR, VF and ECS. I have an APR one fitted and it reduces wheel hop substantially over standard and in my experience hasn't make any real noticeable difference to the ride quality.
The helicoils are basically replacement female threads that look like mini springs and are inserted into the bored out hole where the original bolt stripped the thread. It is my opinion that helicoils are a poor substitute (but in most cases the only option) for the original threads and so prevention is always the right course to take.
For cars that have a substantial increase in power you can buy VF engineering engine and transmission mounts. These control the movement of the engine even more although I would suspect that you would feel more engine vibration filtering through to the cabin with these fitted. They will however give more control over the movement of the engine.
See the link below and click on the second picture of the VF engine mount for more info.
http://www.vf-accessories.com/
