How tough is the install for a DIYer? Looking into shops to put an LSD in mine while changing clutch/flywheel but if the pumaspeed trans with quaife and clutch/dual mass flywheel can be delivered to the US for $2800 that sounds like an obvious choice?
Provided you are at least somewhat mechanically inclined, its a fairly easy job. Having a service manual for the first time is helpful, I believe there is still a PDF of the service manual floating around here somewhere.
Getting the transmission out and back in is obviously the major hassle, its not difficult, just a bit fiddly. Having a transmission jack helps a lot (easier to balance the transmission on than a regular floor jack). It can all be done on jack stands. There is a fancy spreader bar that mounts on the strut towers to hold the engine up since when the transmission is out, you no longer have a drivers side mounting point. But, I just use a screw jack under the engine. You need something adjustable under the engine as you will need to angle the engine/transmission done slightly to pull the transmission away from the engine to drop it down. Make sure you have the front jacked up quite high to be able to get the transmission on the jack out from under the car. I usually pull it out sideways through the driver side wheel well.
Make sure to not forget to drain the transmission before dropping it, otherwise you'll get fluid everywhere. (ask me how I know)
You can drop it without dropping the subframe as well. (I can't because of my 6 point brace, and its actually easier to drop the subframe with the brace rather than just pulling the brace). Note that dropping the subframe opens up a ton of room for activities. Also note that if you do drop the subframe, the two main large bolts are torque to yield, so they need to be replaced.
Once the transmission is out, the clutch/pressure plate/flywheel are easy and straight forward. You will want to come up with something to hold the flywheel from spinning to properly torque the flywheel and pressure plate bolts. Ford has a special tool that you can buy, I just made one from a scrap power window actuator and a few nuts and bolts (imagine my surprise when the teeth matched basically perfectly to the flywheel).
To go back in, just reverse the process. Getting the transmission fully home requires a good deal of adjusting, tweaking, and jiggling the transmission. It will fight you for quite some time, the once its in the correct spot it will just slide right in.
Do yourself a favor and just install a new slave cylinder while you are at it.
The transmission has quite a few bolts of different lengths and orientations, so when I got my replacement I traced the outside shape and mounting holes on a large piece of cardboard and punched out the holes to put the bolts in. (basically like a template so I know where they all go)
There are a few clips, groundings straps and other things that attach using the transmission bolts, so keep your eye on those as they will hang up getting the transmission in and out.
The manual will tell you to pull the starter back and suspend it with a strap or bungee, don't bother. Just pull the bolts and let it chill in place.
Make sure you have a cap or plug for the line to slave cylinder, otherwise you'll lose a lot of brake fluid.
I have done this three times now (soon a fourth when my transmission gets back from Clarke), and the only thing I use the manual for now is the torque specs. So, this first time may be a bit rough, but if/when you have to do it again, it will be much easier.
Feel free to message me if you have any questions.