I have a 93 Mustang GT with a Vortech SQ-Trim and all of the usual goodies.

When mashing on the gas pedal (WOT) while on 5th gear from about 2800rpm , i hear what i believe is the engine pinging as the rpms increase.

This is only happening on 5th gear.

When racing through the gears with the gas pedal on the floor, no pinging is heard.

I've change spark plugs to 2 ranges colder, replaced with wires, checked timing - 10 degrees, cleaned the TB, cleaned the Idle Bypass valve, checked TPS- .95volts, cleaned the mass air sensor & tightened the header bolts... Still the same.

What could be the problem?

 

Mmm. I had that same problem with my 92 GT at 3000 rpms. I was running lean. I had to have the car dyno tuned to figure it out. But are you saying that in any gear at 2800 rpms it doesn't happen, just 5th?

 

For sure a motor sound???, Sounds like 5th gear?

 

I would have someone (mechanic possibly) ride along with you and let them hear what your hearing. I last time I didnt know what something was this is what I did and they knew soon as they heard it what it was.