Rf off the hook

Trying to figure . . . . .
Radio is an RFX'd 25 Cobra 126 watts PEP (wicked loud and clear audio 15+miles)

Truck 08 Pete 379
With everything hooked and ground properly,the radio feedback to the stereo
speakers is terrible.

The Stereo is an after market Pioneer with the CD slot behind the face.
The Stereo is also properly installed.(double grounded)

Now,
Turn the stereo on and key up " F E E D B A C K F R O M H E L L "
Turn the stereo off, " F E E D B A C K F R O M H E L L "

Remove the face plate and then key up........no feedback ??
The stereo is still wired with constant current of memory and security alarm etc.

So . . . . . .