Do I need to go get my exhuast system done professionally. My friend said that the only thing you need to do was weld the pipes on.

 

You some how to bend the pipes. They aren't just all straight. It also depends on what design you want to do with your car. If your coming off the pipe after the cats and then just going a bit straight and then a muffler and then a turn down or more pipe? You need to get under the car or do some research to see exactly what you want.
A mandrel bender is best, but they are very expensive and few muffler shops use them anyways.
I'd recommend coming off the cats going into an x-pipe, then back a little, then your mufflers, then some more pipe to your tips.

Look at a post i made in the 4.0 specific forums about my exhaust experimentation on my 05 v6. It may save you some headache in the long run with what you want to do and what sound you are looking for. The title is Flowmasters vs. GT take offs.

 

if you're putting on GT take offs, it'd be best to get it professionally done. unless you know someone who knows how to weld. if you just get a kit, then it should just bolt right up and you can do it yourself.

if anyone is interested. ask this guy how much he's selling for:

http://classifieds.stangnet.com/show...1&cat=7&page=1