The coilovers look a bit budget, and thus firm, but the beauty of having all the kit is that you can fit and see what you think, and return it to standard if you wish....
Ive heard front upper strut braces are good for stiffening the mk2 shell, but ive not tried one partly because I dont want to drill the holes! With all those parts fitted you will be considerably stiffening the ride and handling of the car, which may be great on smooth race circuits, but be wary of removing too much of its playability for normal roads. Ive found the nice thing about the golf chassis is its ability to keep gripping in a tightening turn etc, i.e. its hard to unsettle it. Dont go too far and create a Peugeot handling golf (if your not going to track it)!