Ok guys, i know this is a stupid question, but what is the best way to install some shorty headers on a third gen with A.I.R.
Am i going to need a torque wrench for this? And also, will i need to weld the Y-Pipe when it gets down towards the cat?

 

The best way? I'm sure there are more than a few threads about it laying around, but if I recall correctly it's pretty straight forward. Take the old manifolds off and slip those in. You might have to unbolt the engine on one side from the motor mount and jack it up an inch to give yourself some more clearance.

Take a look on your Y-pipe and see if it came with a flange to bolt to the cat or not. That will answer your question. Most likely it's flanged and simply needs to be bolted.

 

I jacked up both sides, in turn. Had to unbolt the tranny mount too. The "higher" you get it up the easier it is to slip in.

Torque wrench would be nice. I used a crow's foot and a torque wrench.

Weld, up to you. You can use band clamps too.