Check the picture out. Note the O2 bung before the cat and the bung you can faintly see after the cat. This is the stock system.
http://www.m3post.com/forums/attachm...1&d=1234652392
Another clearer pic of the stock cats. Look at the right side cat.
http://www.m3post.com/forums/attachm...1&d=1235401702
Here is a pic of the AA High Flow Cat. Note the O2 positions. Same as stock.
