Assuming you have a MIG, order some of these mandrel u-bends from Jegs,- http://www.jegs.com/p/Hooker/744799/10002/-1 . Once you get the tubing, you can use something like a piece of wire to make a mock up piece with, so you know what kind of angle you need. Or you can hold the u-bend up there, mark it with a marker where the bend needs to be cut in order to dump the exhaust where you want it. From there, cut it, tack it, hold it/bolt it in place. Eyeball and measure it and make sure it looks the way you want, then work your way towards the back of the car. Weld it up once you get it the way you want it.

It takes a little bit of time, but you end up with a nice exhaust in the end.