Exhaust = less power?...

Fitted Ktec de-cat pipe to my existing Ktec cat back and when pushed the revs aren't as enthustic. My brothers Audi 2.0l desiel (140bhp) kept up with me.

Im assuming the flat spot has worsened and the standard ECU isn't running in tandam with the new mods, so a remap needed?

Thoughts?
 
it will take the Clio ecu some time to work out what's going on so should improve with time but a remap.would be the best option.