So, I have attempted several different versions of getting away from underhood air. After relocating the canister under the headlight, I first tried a 4-inch addition to the stock air cleaner canister (see photo). This very much accomplished getting "cold" air in, but I decided that the stock air inlet tube was probably insufficient for my mild 350 vortec TPI. I based this on the data log kPa readings I was getting over 4,000 rpm; as much as 4 kPa drop. Second try accomplished using 3-1/2 inch from throttle body to a 4-inch inline air filter that was then sealed to the inner fender. There was barely enough space for this with A/C, etc. In fact, I had to find a molded 90 degree hose to clear the coolant overflow line. There's about 3/8-inch clearance to the A/C pulley and less hood clearance than that, but it just clears. The air around here right now is pretty bad (90+ with dew points in the 70s) so I will probably wait until better weather to determine the effectiveness of the bigger intake. I know the stock inlet actually necks down pretty small at one spot, and I figure, hey, bigger's not gonna hurt, right?

 

FWIW, this is what I finished with. I insulated the filter housing with 1/8-inch foam and then overlaid aluminum heat reflective film. Definitely lowered intake air temperature. And I'm sure there's no longer any restriction.

 

That is a really cool design and I liked your first one too using original stuff. It looks like an efficient set up.