kylepeedle

so i did a muffler deleat and dumped it out on a angle befor the rear axle its 2.5" cat back with a 3.5" tip sounds reallly good! but i wanna duel it out the back but im unsure where i need to start the Y pipe for the duels any imput would be great! i have an idea likecut a peice of pipe where the muffler was weld it on then run the pipe that was allready on but cut it some where along the line and y pipe it but ited be nice if someone could help me out here thanks cheers!
2000 f150 4.6l xlt
also the bumpers are rusting out im just gunna spray paint them gloss black but how do i get all the old paint off and do i gotta sand till im on bare metal again or will a little rusty metal be fine? it dosnt have to be perfect i just want it to look some what good