I decided to do some testing today
I mounted my LS3 head/intake/tb to the flow bench and tested the stock airbox w/ stock filter, and stock tube, then I swapped the tube out for a tube similar to that which you would find in most intake systems (4" OD 16GA aluminum tube, ~16" long, 6" CLR)... Much to my surprise the stock intake tube with it's baffles & accordion section flowed more than the tube without that stuff...
The stock tube flowed ~0.75% more (~2 CFM) than the aluminum tube did. While I didn't compare the stock tube to a Blackwing because I don't have one, I imagine the results would be similar (little to no change).
After doing this and seeing the results, IMO the tube is a waste of money, all you'd get is more intake sound due to the lack of the baffle box.
The filter: I did compare the stock filter vs an S&B filter @ .500" lift on cyl#3 through the top end assy.
The S&B filter flowed roughly 1% better through the intake system/tb/intake/head @ .500" lift... (appx 3 CFM more)...
I have... And you'd be surprised at the results.