Thanks for all the replys.
I find it interesting that one can improve on FE and performance over the factory and still pass emissions.
I have tuned over 10+ cars that have reported fuel mileage is now better then stock. Also 8 of the 10 of these vehicles are now FI.
I think that at the OEM level they can't get to aggressive with there timing tables. Plus they don't have individual timing and and fuel trims etc.