Before you go spending money on remaps and/or changing exhausts have a look at this little fix -->
http://www.clio197.net/forum/showth...aded-FLAT-SPOT&p=445291&viewfull=1#post445291
Checked my map sensor today and it's loose as anything, zip tied it down for now but going to get some easy gasket or something to make sure it's 100% sealed. Seemed to improve it but I will know in the morning if it's worked as my car was quite bad from a cold start for the first few minutes of driving.
Worth a try for 5-10mins of work. Just be careful removing the sensor, people have said it's best to do it after a run so it's warm and the plastic won't be as brittle. A few people have managed to snap the sensor ending up having to remove the inlet manifold to get the bit that fell in out lol.