ive been having a problem around the 4000 revs area when driving hard, its like hitting a wall for a second before continuing to higher revs. The car is a MY00 and running around 330-350bhp. any ideas ?

 

bump :P

 

Hi,
$000rpm with pedal buried in the carpet is the point at which you will have maximum charge pressure (boost) at the inlet manifold, particularly in 4th or 5th gear. Sounds to me like the boost level is exceeding the set level in your ECU that cuts the fuel until the boost level drops to a safe level
Kevin

 

so it sounds like a problem with the mapping then?