To be perfectly honest. FMUs suck and are hardly a good tuning tool. An FMU is only a very course way of "tuning" and does nothing in terms of tuning across rpm cells has ZERO effect on ignition timing not trimming based on temps, etc. I personally wouldn't even consider an FMU a tuning device.

However with that said I am also a realist. The truth is the stock computer on that vehicle is probably safe enough in terms of fueling and more importantly ignition timing (and knock control) that with a centri blower at low boost with premium gas everything is probably safe enough... not ideal but not bad enough to take itself apart. While the mileage is not a great indicator it seems that it backs up that theory if in fact the blower has been on there for a while.