[Ron1]

Just so I could never be accused of being closed minded, I decided to call a friend who has spent the last 20 years working on Fords and the last 7 working on performance upgrades on 5.0's with the focus on EFI 5.0's. Here is what he said. If you look at the cams in a carburated vs. EFI 5.0, there is a difference in overlap. When you talk about a carb'd 5.0 you want zero backpressure, because you can tune the car easily for the system and its components via carb, jetting and timing, etc. On the EFI 5.0 you have to be careful. Because the cam was selected to work with back pressure, if the ONLY change you make is in the exhaust system, you may loose some bottom end torque, but you will pick up some top end HP.
You will most likely see no change in your track times for that reason. I then asked what he would recommend, and here is the tricky part. In order to compensate for the design of the motor, it having been designed with a full exhaust, and NO other changes are being made, he said that try to keep the backpressure around 1.5 psi, but if it creeps up to 3 to 4 psi you will begin to loose power. He also said that in a case where you run N2O or a whipple charges and the computer has been updated, the question goes away, because they will more than make up for any loss of bottom end grunt.

In short, I think that everybody was correct. The question still remains, how do you tune for that, and again, this is where its gets tough.

Just one other opinion.

Ron