The car is an MY00 with the following performance mods: Tek2, JR Panel filter, full de-cat.
Since having the down pipe fitted (Magnex twin dump) it seems that the fuel economy has increased markedly. On the last two tanks I have been getting approx 350 miles! Admitedly I have been doing longer jorneys than usual, but at best I was seeing 280+ miles / tank previously.
It may well be that there is no connection with the downpipe fitment but I am concerned that the car is runnning lean. There are no obvious problems with engine idle (faulty MAF), and the boost gauge is indicating the right levels of boost (1.1 to 1.2 bar).
Any thoughts or comments would be appreciated, before I book it back in to Prosport for a check up.

Cheers
Simon

 

If your car was running lean,surely the hotter running of the engine would cause some sort of det which would be displayed on the knocklink assuming you've got one fitted.Just a thought

 

Almost certainly a failing MAF. If you know someone with deltadash get them to check it out. Peak airflow should be at least 4.28V usually between 5500-6500rpm. Alternatively reset the ecu, fuel learning will reset and this may show up the unstable idle. Or just replace the MAF (~£75)

Simon