per side, the intercooler sees 199 cfm at 15 psi. There are lots of variables as you have mentioned, and these make things pretty complicated. Particularly the 414 cfm at the air filter. It may be much more than 414 due to the vacuum created. This is part of the reason I think the pipes from the filter to the turbo are so critical.
Larger high pressure pipes slow down the air flow and I think this greatly improves the intercooler efficency. I calculated stock size pipe air at about 100 mph. This just shoots across the center of the intercooler. Larger piping lets more of the intercooler cool the air more effectively. I calculated 21% more air mass with 80% intercooler efficiency vs. heat soaked. This is huge. Pipe pressure drop- not so much.