Quick questions about taking off the mid-pipe
 

So I've read a few places that the nuts that attach the headers to the mid pipe are melted on to the bolts that protrude from the mid pipe. I could crawl under the car but i'm at work and its 30 degrees outside so I was hoping someone could tell me more about how the headers and mid pipe attach. Is the bolt welded to the mid pipe flange? or are they separate? Were nuts at some point in time not welded to the bolts? As in, did they just over time become welded to the bolts like most exhaust nuts and bolts do or did someone at the factory actually weld them together?

Last question, so they have to be torched off. What does that mean? Just heating the nut and taking it off normally with a ratchet?

The triangulated flange mounted on each of the headers / mid pipes have (IIRC) one welded bolt with a nut/washer. The other two are studs which are push through and tightened again by nuts/washers. Non of mine were welded up.
Your biggest challenge would be corrosion which can be a mongrel to break loose the nuts & bolts - ie gas torched off in really badly corroded pipes.
Best replace them all with S/S when installing new pipes & clamps.

I think I'll let some pb blaster set on it overnight a couple nights and see if the nuts will come off. Im in AZ and the cars always been here so theres very little rust on the car.

When I replaced the clutch on my '07 Cayman and '99 Boxster I removed the exhaust as one unit by disconnecting it from the exhaust manifolds.

The solution which worked for me was to tap on the tightest fitting socket I could find and then break them off with an impact gun. Take a grinder to the welded nut to remove it.

I replaced the hardware with new nuts and bolts along with a good amount of anti seize compound.

The benefits of a dry climate really helped out. The bolts and the nuts all broke loose without much incident. New tests pipes are now on and muffler is on the way. Happy days.