Would going from the ugly Ford stock intake ELBOW (only) to the smoother better looking plastic Steeda ELBOW create a cause to have to retune the Shelby GT?

i dont know, i have thought about that route too, why ford/shelby only did halfass job on the intake i dont know. but i cant imagine you would need a tune. i could be wrong, but dosent a tune come from changing the MAF size from one size mm to another? as just the elbow would not cause it to collaspe at high rates of flow, as demonstrated in a video put out by "muscle mustangs and other fast fords"

You should go for the new Bullitt intake, it is much better than the old FR setup!!

can you squeeze the stock Shelby GT tube?
If so then yes, there might be differences built into the stock tune that acount for the tube getting smaller at high intake rpms. The stock Mustang tubes actually compress when attached to an aftermarket CAI filter, which allows in so much airflow.

yes, you can squeeze the stock tube, as it is the same in the v6/gt. however, isnt it a bad thing it can be squeezed, for that reason all the aftermarkets are hard, either plasic or metal? im not going to buy a tuner for the SGT just for a tube though, i spend enough money trying to keep gas in the shelby and my lightning