I used an AP XLerator XS 2288 18" body 24" overall 1 x 3" in 2 x 2.5" out . Stainless Steel 4" x 9" body....Very similar to the 18" Magnaflow. I think the MF is 5x8. Half the price of the MF. Quite happy.
Magnaflow muffler #12288 it is 3" in and two 2.5" out the back. Very pleased with this check out https://www.youtube.com/watch?v=J2r1BOqyfLE . He does a very good comparison and that's what made me buy this. P.S Just a heads up at the end of the video there's a zombie that pops out and screams so keep the speakers low towards the very end.