He's not, mines been chipped, and i have a rolling road print out saying it has 247bhp, and it appeared in Total Vauxhall with that figure, but i've also had it rolling roaded at 199 and 228bhp, so make of it what you will 
As you have discovered, rolling roads vary greatly in their accuracy, or lack thereof. Quite frankly, many just tell the punter the number he wants to hear so he goes away happy with a figure to brag about down the pub.
Unless the losses are properly calibrated out of the measurement with a coastdown on each run it's guesswork, and even then, it needs a good operator and a decent set of rollers to achieve consistent figures.
Personally, I doubt you could get anywhere near 245BHP out of an X30XE without internal modifications in addition to induction and exhaust work. It's certainly beyond what a simple chip change can achieve.
Kevin