My car has just had the JCW 210 kit fitted and I'm hugely happy with it - great noise and excellent performance.

However, when the car gets a bit hotter (e.g. after 100km or so) the engine begins to stutter slightly when I floor the throttle, especially between 2500 and 3000rpm.

Has anyone else experienced this and what can I do about it?

 

Install one heat range colder spark plugs and make sure they are gapped correctly. Sounds like your knock sensor is retarding timing under high-load/low-rpm situations (an ideal condition for knock).

 

Get a dyno tune from Jan at Revolution Mini Works and they you will be feeling a whole new side of your JCW.

 

If the knock sensor is retarding timing then its doing its job. It is a listening device, it will only retard timing when it "hears" audible pinging. Also the JCW kit comes with colder plugs.

 

took the car into the garage and got the spark plugs changed under guarantee - car is now running perfectly.

 

You're welcome.