the charge cooler can get a blocked nozzle so people say best to sitch it and get an intercooler. bushes wear just like any other focus, especially the two rear trailing arm bushes (the two that have the bar going through them and bolt upto the bodywork). just had to do mine on my 2l zetec and by fay the easiest way of doing them is by dropping the whole subframe as the other bolts sieze into the bushes and either dont undoo or rip the bush to shreds and then you still have to chop the bolt to get it out. also i replaced my bush with the energy suspension poly type which can be fitted by hand, with a little persuasion. (anyone requiring info on these and help can pm me)

also if it torque steers excessively the front lower arm bushes are worn so easy fix.

also rust, personally before it starts to rust badyly i'd tidy up all the little bits then book it in for a full rust proofing with rust.co.uk or buy one of their kits and apply it yourself.

i cant remember if the rs has an alloy thermostat housing or not but if it aint its worth upgrading to one as the plastic ones crack and piss coolant out in seconds.

there may be a few more that i cant remember but in the main very good cars, ripe for a tune to 300bhp and i think that would be just about perfect with a decent set of tires!