The muffler on my 04 SR5 rusted out and I have a replacement Gibson on the way. It seems like a straightforward job, but my biggest concern is the spring bolts connecting the catback to the catalytic converter pipe. After 15 years of salt ridden winters, they are quite rusted. Cutting them seems like the logical thing to do, but it looks to me like the "nuts" are welded to the flange?? What do y'all recommend? Picture in link below. Thanks.

Shared album - Mike Pudlowski - Google Photos

wire brush the threads that are sticking out and spray pblaster on the bolts to try to get them to loosen. You could always heat up the nut part with a torch to get them to loosen. If all else fails just cut the whole thing off and get a new one from Toyota.

I cut mine off with an angle grinder. I don't recall having issues getting welded nuts off but it's been awhile since I did the work.

I had those bolts torched off!!

If you plan to use a 'donut' type gasket, I needed to get a pair ~4" bolts to make that connection, using the springs..

I used Evil Energy band clamps for the connections...(not the supplied clamps)

(4.7, V8)

When I installed my TRD dual exhaust I had the same issue with rust, so I just zipped them right off with a cutoff wheel. I went to Napa and bought the replacement bolt kit which came with all new springs, washers, etc., but no nuts. I don’t remember having to cut the nuts off the flanges, so they probably weren’t attached. I just ended up going to Ace hardware with the bolt and found a nut that would fit, and bought a couple to finish the assembly. No matter what you do, spend the $10, or whatever it was for new hardware because not only will it make your life easier, but having new springs will keep that flex joint working as designed. You can solid mount it if you want, but Toyota must have had a reason for putting a flex joint there, as opposed to solid mounting. Most cars have some type of flex tube in that area because of engine movement on the rubber mounts. My assumption is that over time, this will cause a solid pipe to crack. On my daughter’s Camry, there is a short section of braided stainless tube in that transition, and it recently failed, so now I have to either replace the whole thing, or see if I can find a shop to cut it out and weld a new flex coupling in.

If you don't cut, use this!

I agree. I generally always try soaking hardware in PB first, but in the case of older exhaust hardware, they almost always end up snapping anyway. When I was was younger, I’d spend hours trying to work at rusted hardware. These days, I just don’t have the time or patience, so if it doesn’t budge after a few tries, I just cut it and move on.

Exactly. When you look at them and can't see any threads left then the cutoff wheel comes out. The exception is the nuts closer to the header, they seem to come off ok. I usually use a wire wheel on them, lube and zip them off.