Under the car, 3 or 4 feet behind the driver's side front tire, and about a foot or so in from the rocker panel. It's mounted onto a little support cage you have to remove first--3 bolts I think. The filter metal's thin, so be careful with the wrench when unjointing. Soak the joints and bolts well ahead of time with PB Blaster. Some people suggest using new copper washers in the joints, though I usually don't. Check carefully for leaks before driving.