Jonesy, K4M is the 1.6 16v engine.
At the moment I still have drums at the rear and 259mm (brembo oro) discs at the front, theyre enough to stop the car (actually, the stock 1.6 16v Clio has the same brakes from the 1.2 16v, except the ESP version with discs at the rear).
The engine swap was in fact very expensive, but not due to mechanical reasons (that part of swapping the engine and stuff was rather easy actually), the REAL problem was the electric part. To cut a long story short, the only way to do this (if you have a phase2 Clio2) is to get the engine+ecu+cables+electric throttle body from a phase2 Clio2, because this is the only Clio that uses multiplexing. And believe me, finding a crashed phase2 1.6 16v is VERY hard! (Id say impossible!)
As a matter of curiosity, Renault has sold less 1.6 16v Clios in Portugal than Clio RSs, in fact, one of the largest Renault dealers here never sold a single phase2 1.6 16v Clio2!
This engine swap is something I really dont recommend, unless you have a phase1 Clio2 - in this case its a rather easy task, and something to cost less than 2000€ (better cost/performance ratio than fitting a turbo on the 1.2 16v!).