Don’t ever believe dyno results that a manufacturer or aftermarket vender publishes on a product they sell. Don’t ever believe dyno results that you read in a magazine. Running a Ford EFI controlled engine on a dyno will not provide accurate results unless the operator knows how the EFI program works. There are only a hand full of people in the world that truly understand it, and even fewer people that can run a dyno properly. Dyno’ing a Ford EFI controlled engine is usually only a cool magic trick. The way to properly dyno is:
1. Clear the memory from the computer.
EEC-IV can be cleared by disconnecting the battery for 15 minutes.
EEC-V can only be cleared by the Data Link Connector.
2. Run the engine at operating temperature for at least 5 minutes.
3. Do not shut off the engine after the 5 minutes prior to the dyno test.
4. The vehicle must repeat that cycle for each dyno run.

I don’t know of many people in the country that do it correctly. Call the manufacturer of the performance product you wish to purchase. Ask them what their dyno procedure is for product testing. I’ll bet you now know more than they do. If you don’t clear the memory the computers program is still adjusted for the last engine configuration. If the dyno is run prior the engine being ran for at least 5 minutes the computer will still be in the start up program. Failing either step will not yield accurate results!. Shocking isn’t it? I am in no way calling all the aftermarket venders liars, they simply don’t know any better.