Tom, I think R32_T misunderstood your question -
The R32 does not have coilovers as standard, the ones you are referring to (for sale on uk-mkivs.net?) are aftermarket parts. However, the rear suspension on the R32 (and all other 4motion models) is COMPLETELY different to the front wheel drive models like your 1.8T. In any case, even if the coilovers would fit the rear of a FWD Golf the spring rates would be completely wrong due to the heavier weight of the R32. You would be better off buying suspension components that are tuned for your specific model.
With regards to the exhaust - as the rear suspension is different, again this is of absolutely no use on a 1.8T Golf. The 4wd models (Golf & TT etc) have a large silencer that is mounted across the back of the floor right where your spare wheel well is so it will never fit I'm afraid. Also, being from a naturally aspirated engine, it the R32 exhaust might not do the performance of your turbocharged engine much good anyway.