Newbie with an exhaust leak on his '06 Yaris

[Lemayilleur]

Going to go ahead and revive this old thread. Might as well keep all the info in the same spot...

My wife's 2007 Yaris hatch 1.5 exhaust has been "leaky" for over 2 years. It started off has a light "whistle" that was only noticeable during take off. It got worst in the past month until it became "straight-pipe-loud" 2 days ago. I thought it was the header / exhaust manifold, but not quite...

I've looked at it today and there's not a piece of gasket left between the manifold and mid pipe (cat). 1 spring was missing, and the other one was hanging onto the bolt - I took it off by hand... It looks like the bolt got so rust out that the springs managed to pass over the bolts head. But the bolts are still keeping the mid pipe from falling off.

These bolts are rust-welded in place. I tried vice-grips but it didn't move, and I barely have any room to work. I obviously have to break/cut/drill out the old bolts. But I'd really like to do so without taking the header off the motor as I am worried I'll open another can of rusty worms there...

What would you guys suggest.

Picture attached. Bonus picture of the bolts/spring for future reference.