Im getting my Magnaflow tomorrow and im wondering if i could do it myself. But i have a few questions:
-Does the car need to be up on a hoist to do this?
-Does the cat bolt on or weld on?
-Will there be any welding to do?
Thanks for any help

You need a jack and jack stands or a lift and basic hand tools. The hardest part will to get the stock exhaust off, you will more than likely have to cut it in 1 or 2 spots. The catback should then just bolt right up.

So no welding? How long did it take you?

It took me a couple of hours laying on my back in my garage. With a lift and a torch to cut off the old exhaust it would only take 30 -45 minutes.

very very easy. Like he said, once the old exhaust is off it's cake. You will need a sawzall or cutting torch. I suppose you could do it with a hack saw but it'd be difficult.

I did mine at a Jiffy Lube, thanx to my bro-in-law, and the old was definately the PITA! Just a tip, after you bolt it on and listen to your hard work go and get it welded. Mine kept coming loose till I had it welded up. If you have a friend that has a welder and can weld have him help you out as your putting it up. Just my two cents.

If you bought a new cat with your system, it'll have to be welded on.
Or leave it off, and just do from the cat, back (which is what is normally included in the Magnaflow 15620.)

Sawzall with 3 blades and the old one was off in 15 minutes or less.
New one bolted up within an hour, and another hour or two straightening, aligning, admiring, et cetera.

If one had done this before, and went all out at the job, I'd bet you could be done in less than 60 minutes.