When driving off boost quite sedatly i have kind of a surging not like a big hessitation or anything, any ideas it's standard uk 2000 with a ninja cat back and cottton air filter!!

 

Those symptoms can occur if the lambda sensor is faulty. It measures the amount of oxygen in the exhaust gasses and alters fuelling to get the target value and the 'best' burn. Try unplugging it (it's on the downpipe after the turbo) to see if the problem goes away. Its signal to the ecu is ignored when you are 'giving it some beans' so you won't risk any damage to the engine, although you may get a 'check engine light' come up.

Kevin

 

Humm ok i'll try that i've just brought my shiny new de cat down pipe so may try then, Thank you mate