Originally Posted by 5LITER_MUENSTER View Post
I called ford racing and they said that it will sometimes make drivetrain noise more apparent due to increased throttle response. BULLSHYT!
I would guess Ford Racing was telling you the truth. The ECU doesn't have any drivetrain parts to control in a car with a manual transmision that is cruising in 6th gear. What the ECU tune "could do" is shut down the fuel injectors faster, when you take your foot off the throttle, to generate more aggressive "engine driven deceleration." The "thump" you are feeling certainly is likely from "slippage" in the clutch, transmission, driveshaft or differential, but it could be a loose motor mount or something else that is reacting to "hard engine decel." I would consider going to another dealer - one that sells Ford Racing Performance Products in the Baltimore area - and get their "drivetrain guy" to drive the car and observe the problem. Even if you take off the tune, there is almost surely a "physical issue" in the drivetrain.
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