All is well now. They did an excellent job! Now we can continue to dial the newly installed Radix in.
While she was in there I replaced the Chevy OE side moldings with the GMC all chrome Javelin units. Much better! My signature page photo has been updated to show them.

 

Did you dyno after the Radix?

 

...and the gains were substantial but less than expected by both parties.
As far as I know I am only the second 05 Truck L33 5.3 H.O. to do the Radix. My dealer and Magnuson's customer support have been Stellar and I have been assured the expected gains will be achieved. I am confident it will happen.
I don't want to write it up until it is all done.
I will say everything runs great and although the full potential still needs to be coaxed and tweaked from her, she is lots more fun to drive. It fired right up, runs smooth and if I drive like going to church on Sunday the mpg highway is the same if not better, and the City only suffers by 1 mpg. A boost\vacuum gauge is a must. If I can keep the vacuum at 8 or more the milage is great.