I've just sold my RS2, and to be honest I wouldn't bother with another one again. The gains are so little for the money you're paying, mine mapped to 185bhp with approx 150 ft/lb torque, the torque curve was pretty flat which is good for a daily driver, but you lose top end torque as a consequence. People will argue that the spread is better than peak, But when your driving fast and the revs are high the top end torque is lower with the RS2. My old 182 with standard airbox and aftermarket panel with 98Ron Map felt quicker and measuring speed at certain points on my normal drive give evidence that it was indeed faster (speedo may be at error here as we're only talking 2-3mph).
You'll also most likely end up wanting cams and another remap once you've got the RS2 if you don't go down that route straight away, so there is another £1000-£1500 on top once you've added the belt change too. So you're at £2k-2.5k for a clio with around 200bhp.
When the RS2 came out it was big because no one was offering anything better. You can now go down to Engine Dynamics and hand over £2500-3000 for a low boost turbo install that'll give you 230bhp and over 200ft/lb torque.
I guess it depends what you're looking for and whether you want to stay N/A. But if N/A is want you want i don't think it's worth spending £k's for an extra 20bhp. Decent exhaust, and intake mods and efi mapping should see you hit 185bhp. Spend the rest on suspension setup and sticky tyres if you want a faster clio.