When I stomp on it, I hear a rapid ticking sound which seems to be coming from behind the radio area or in front of the shifter. I don't think it's detonation (pinging) because I've been dealing with that lately due to custom tune problems, and it doesn't sound like that. (I'm back to stock now, so no pinging). This sounds more like a tazer gun or sewing machine. It's only at WOT - any speed. I put the car in neutral at a stop an revved it above redline, and I do not hear the ticking. Any thoughts?

 

There is a TSB for a similar issue that has to do with a loose hanger on the trans cross member in that area.
http://bradbarnett.net/mustangs/gala...sb06_04_01.pdf

 

I think that tsb is teh exhaust isolator rattle, which is at low rpms. I had that before I installed my GTA exhaust - different rattle.

 

Reported as coming from the center stack in front of the shifter. How does axle backs fix that? Less vibration with the GTAs?

 

I have no idea. Less restrictive maybe? I know I'm not the only one this has happened to.