First I need to go out and get some ratcheting wrenches because the damn sensor on the header gets in the way of the socket wrenches. And I need to find a way to remove the O2 sensor without breaking it off the cat.

And the new cat doesn't include any moutning bolts/nuts. My question is, the stock cat seems to have bolts attached to it that connect to the catback exhaust, but the backs are near flat and rounded wth over!?!? What size bolts are those because I already have the nuts for them?

I can just use the stock nuts/bolts/springs for the front, just need some bolts for the back.

 

the bolts on the stock cat are attached to the cat, and will not come off, as you noticed. The bolts you need are the same as the bolts that should have came with your catback exhaust that connect the different exhaust flanges, instead of using the stock ones. Take one of those off the exhaust and to the hardware store and match it. You'll need to buy 3 of those, and some nuts (lock nuts!, not the nylon ring locknuts!)

I have no idea how you will get those cat bolts off.

 

well for the back you can always just use a cut off blade and cut off the welded on nuts, OR use a drill and drill the threads out of the nuts and just get some longer bolts and nuts, either the nylon locking nuts or just 2 nuts per bolt and jam them on there.
and while its off ya might want to replace the gasket/donut seals on the system. those spring bolts are a PITA because the bolts are just long enough. ive had huge problems with instaling those springs with stock bolts with new gaskets. a bolt thats only 1/2inch longer will make it ALOT EASIER to instal those spring bolts!
i deleted the spring bolts on the front cat.