I have a 416 Trailblazer with 1 7/8 ths headers and 3" collectors that run into a dual inlet dual outlet Magnaflow dumped before the rear axle. Once I spray it I will make a far about of power. I was thinking right where the header starts open it to 3 1/2", run a 3 1/2" X and dual Borla XR1, again dumped because of how low the truck is. The cutouts are oval type shape, should I put them on the 3" side of the collector or the 3 1/2" side. Before you ask why I don't run tail pipes is because I have coil overs all around with 28" tall tires and it is almost tucking front and rear tire.