A lot of very confusing/conflicting posts!!
The R-Sport ECU cannot possibly be the same as the Clio Cup Race Cars for one very simple reason - they use a completely different ECU setup which has no relation to either the 172 or 172 Cup road cars. Plus, the racers are based on a Mk1 172 setup, which doesnt have the fly-by-wire throttle.
Despite all the rumours, the Mk2 172 and 172 Cup share the -same- ECU. The part nos might be different, but this reflects the different model its fitted to - other manufacturers have done this for years! The only reason the Cup -feels- quicker is because its lighter and handles better...period!
5% is bugger all! An 8.5bhp increase will be barely noticeable in terms of sheer power. Ditto the torque. The key here is drive-ability. Hopefully, this is where the real improvements are - ironing out the flat-spots. Bear in mind, R-Sport probably have their hands tied (as well as struggling to get reliable power from an ECU mod) since the engine is already highly tuned and they will have to keep one eye on reliability - after all, Renault wont want them selling these things and then getting a whole load of warranty claims for engine problems, now will they?!
Your £200 would be far better spent on a good track day, with some expert instruction, where you can learn to drive your beloved 172 to the limit (and back home, hopefully!). Learning how to master the cars ability will always out-weigh a few bhp gains from chips and the like.
</rant over>
