Same reason I added 20lbs of sound deadening, kept the factory A/C system & everything else. Also, I was able to run the vent using the factory drain hole behind the LH rear tire
BUT- I already gained a bit by moving it to the trunk. I don't drift; and I will never realistically push it on the touge/circuit/backroads hard enough for this to be a problem.
AND... This way, I have very easy access to the fuel pump carrier without having to struggle with the carpet. Trying to balance aesthetichs, performance & maintenance-friendliness~