Look at this PIC- Are these Mil eliminators?

[mlambrecht82]

When you remove your catalatic converters the ECU corrects the A/F to run the car lean, because it thinks that the car is putting out too much emmisions. If the MIL's from Dallas mustang don't correct the A/F then you will need to get a pro-M optimizer, if I recall right they are somewhere aroung $300-$400. The car will probably run a little lean, but when you floor it your A/F should be fine. As long as you don't get any detonation you shouldn't have anything to worry about. (you might get better gas milage) The pro-m optimizer could be a very useful bolt on for your car, you might be interested in getting one even if your car isn't running that lean. It should be running lean though as far as I know. I believe that Brother's performance told me this. Hopefully someone else on this forum will back my statements up, 'cause I'm not an EXPERT on the 4.6.
Anybody out there know what I'm talking about?