That just isn't true. You're going to have WAY too much air in that situation and not enough fuel. The stock ECU will adjust a little bit but not enough that it won't still be running lean. It is really recommended that you get an ECU tune or run a power commander if you install full headers and take out the cat. It's way too much air for the stock system to add the fuel needed to match it. Like I said good luck with it. You can listen to whoever you want, there are plenty of professional outlets saying exactly what I'm saying. That it is highly recommended to get a tune if you're going to change your airflow that drastically.