What do the bolts that attach the cats to the manifolds look like? Are they through bolts or studs that come out of the manifold or what? Are they easy to break or strip? That is my main concern with doing this myself. I'd crap my pants if I broke off a manifold stud.

 

The cats have 2 studs on them and there's 1 stud on the manifold side for both cats. I didn't have a problem with that whatsoever and didn't spray them with PB blaster or anything. They came off pretty smooth without a ton of torque needed. Having said that, it's a good idea to spray them pretty liberally with PB blaster first to make sure but overall I didn't have problem. The O2 sensors were a different story and I wouldn't recommend trying to remove them with the cats still attached to the exhaust manifold. It was a battle trying to do it underneath the car where I couldn't use a big enough box wrench to put any real torque on them. Taking the cats off and being able to use a bigger wrench with a full range of motion on the O2 socket was a breeze.

Oh and like davidv said remove the two exhaust manifold bolts from INSIDE the engine bay on the driver side cat. It was much easier and I don't think it's even possible to do it from underneath the car. I removed all of the passenger side cat bolts from under the car.

 

Is it generally a feasible task, or will this frustrate me to tears...The mechanic stripped my 02 sensors putting my hi-flows on, and a honeycomb got knocked loose and lit the car on fire...so if this is do-able without a blowtorch I want to do the test pipes myself. Also, what should I be looking at installation-wise for tp's if I decide to go that route? I think I was jipped by the other guy too.

 

What do you mean a honeycomb got knocked loose and lit the car on fire?! I'd say it's definitely something you can do on your own. Most places will likely charge $150 on the low end and $300 on the high. Anything more then $300 is a rip off IMO. Do it yourself and be more satisfied with the results.

 

hfc's have 'cells' in them which restrict exhaust gasses, but allow more flow than stock cats (mine had 10 cells). One of them got loose, and rolled around the exhaust. It then turns red hot like a piece of coal and will burn through whatever is above it. It's like gasoline doused kidney stones for your car.