Poor fuel economy from B5.5 130PD

[RogerM]

I've been running my 130PD Highline for about a week and drving it no different to my tuned (140bhp ish) B5 AFN engined car and I'm only just making 40mpg compared to the 50+mpg from the B5 AFN, what might be the causes for this, are there any known 130PD issues to look out for?

To make it worse my B5 was on 225/40/18 and the Highline is on the stock 205 tires.

Nothing seems to be leaking boost etc and it goes very well but seems to have a thurst!

Thanks in advance