I got the 904 original to the car. When the PO swapped the 318 with a 340, he/she kept the 904. It seems to be working fine on mine with a basically stock 340. TCI sells a version of 904 good for up to 400 HP non supercharged. I think you can get higher capacity custom version from A&A. I read 904 is lighter and has less losses than the 727.