Think so .. Sean called me yesteday and reckons it's the spark plugs. NGK Iridiums o a EJ's with some boost doesn't go too well apparently.
Despite them being pulled out and re-gapped the issue remained. Sean's pulled them out and replaced them with some Platinums. He's got the car at the moment and seeing how it goes.
Hopefully all sorted.
Would make sense though if it is them, as they wouldn't cause a CEL, or any
ECU error codes. He's also checking the AFR's and stuff too!