Hi,
I have already conducted tests using a local exhaust ventilation system. Audi A6 2.5 AEL.
Specifically, I installed a radiator fan from a Golf behind the intercooler (under continuous load) after doing some sheet metal work.
It's quite a bit of work to assemble this thing, and there's very little space to work with.
Therefore, I also made a mistake => In my opinion, the additional cooling is significantly noticeable both when starting from a standstill and in city driving, but the effect diminishes on the highway. <<< In this case, the fan also burned out due to the lack of pressure equalization flaps.
I haven't had time to replace and improve the fan yet, but I definitely will. The car feels more agile from a standstill and generally more responsive (my impression; I couldn't measure it precisely, except for the hill climb test, where it was about a second faster).
Best regards, Frank.