SoCalSprinter,
You describe your noise issue as "droning".
A turbo noise is at very high frequency and would commonly be called "whistling" or if there are mechanical issues "screeching".
Since you have the Dash App, why not take a look at the turbocharger
output pressure?
Watching the engine load is good, but if your App has a PID (Paramater Identification Code) for "MAP" (Manifold Absolute Pressure in PSIA) or "Bst" (Boost=Turbo output pressure in PSIG) you can see how well your turbocharger is working.
If, when you are accelerating you see the MAP go to > 34 PSIA or the Boost go to > 21 PSIG there can
be very little wrong with your turbocharger.
I took a quick look at the Parameters available on the Palmer Performance Dash Command site and it looks like Intake Manifold
Absolute Pressure is available, so simply set the Intake Manifold Absolute Pressure as one of the PIDs your Dash Command is monitoring and you should be able to see very quickly what your turbocharger output is under full acceleration.
If it's > 34 PSIA your turbo is working normally.
If it's in the 20-30 PSIA range (at full throttle) you may have some issues.
If it's < 20 PSIA @ full throttle, your ECM may have put you in Limp Home Mode (LHM) for either a too high
or too low MAP pressure which could be the turbo, but more likely a MAP pressure leak somewhere in one of
the hoses, the intercooler/Charge Air Cooler (CAC) , or one of the hose joints.
If anyone near you has a DAD unit, they could very quickly run a quick interrogation of the ECM to see if there
are high/low MAP pressure events stored.
That will give you the solid information you need to trouble shoot what's causing your noise.
Be aware that too much MAP is just as likely to cause LHM as not enough MAP.
The computer "expects" a certain boost pressure at a certain RPM/% engine Load level and if the
turbo is not being controlled (by your electronic turbo actuator) correctly, the sensors will signal the
ECM that there's an issue and may set LHM.
Sounds like your problem is just the noise, so that's a good thing.
Also, some people really don't like the increased sound levels that you get with the Riordan Turbo
Resonator Eliminator.
Might want to change it out for a cheap Dorman aftermarket resonator to see if it's the un-damped
sound of the turbo (or one of it's harmonics) that you are able to hear as the "droning" sound.
Roger