XRAY - Model racing cars

Can the catalytic converter and exhaust be removed as one piece? Do I need to unbolt the rear section of the cat from the rest of the exhaust via the ‘spring’ bolts on the back end of the cat? I’m replacing my exhaust (nothing fancy, just pretty shot) and I don’t have a torch to cut through one of those rear bolts with the spring around it. It’s the single most ‘stuck’ bolt I have ever encountered. I’ve had no luck with breaker bars, direct heat from a hand torch, penetrating chemicals, or even candle wax, etc. if I can just drop the whole thing that’d be the bee’s knees. Cheers guys!

Clarification edit: I had to gut my cat recently until I could replace the exhaust, and only had to unbolt the front of the cat from the exhaust manifold, but that’s how I discovered the back was seized. I don’t have it up nor the new exhaust yet as it’s in transit now, but would love to know if I can avoid the headache right off the bat.