I've seen a number of turbo and down pipe set ups that claim to retain you A/C with out having to do any mods. However the positioning of the down pipe and compressor housing vary. This question has probably been addressed a million times but which side should the down pipe be on to keep the a/c and which side should the compressor be on on my B18B1. Also, most of the T3/T4 turbos I've seen appear to have the compressor exhaust pipe directed towards the radiator. Can the compressor and turbine housings be rotated so the exhaust pipe points down? Or is this the best set up?

Most a/c kits do require some minor mods to retain a/c, like modifying the a/c bracket, ect... I believe most kits, like the full-race kit in my sig, point the compressor inlet towards the passenger side and the turbine towards the driver. I'm not sure what your asking about pointing the exhaust straight down, but if you are wondering if you can point the turbine outlet towards the ground, then no you can't do that because the oil drain and feed need to be vertical.