..what? the headers have nothin to do with the fitment of the muffler unless u ran a muffler right off them.. as i know it, it comes with a straight pipe to get ride of the cat. it would bolt one side to the y pipe, and the other side to the S bent(not sure if that is part of what they call the B pipe) but if u wanted a high flow car you and going to have to get some welding done. were you decide to weld it in between or to weld 3 bolt flanges to bolt up. because the magnaflow cat is less than half the length of the stock cat. so you will have to buy some straight exhaust tubing. (only need about 12 - 18 inches but idk were they sell it that short) i know jegs hase aluminized 2.25 pipe what is 4 foot long for like $10 plus shipping.