The reason it works on a supra is that it sits straight up and down with lots of room on both sides, BMW has the engine leaned way over to the passenger side, so there just isn't any room on that side and all the room on the other side.
It historically worked good when the exhaust w just a pipe and the intake was rather large, but now leaning the block the other way would make more sense and simplify things greatly!
2008 E93 335i, MHD, HPF IC, Injen Intake
2016 X5 M-sport 35i JB Stage 1
2013 Mercedes C63 AMG ROW airboxes, power pipe, Eurocharged V6 Flame tune 540 HP