Does this Walker/Starla stuff just leak everyplace, or don't I know anything about fitting new exhaust parts?

The '89 740 turbo failed inspection due to a prematurely rottd over-the-axle pipe where the joint at the rear muffler was leaking and corroded the pipe from the outside. Volvo pipe, Audi rear muffler assembly.

he wants to charge my $60 just for the axle pipe and I know for about $75 I can get the axle pipe and replace the front muffler, too, which is starting to go.

I salvaged the Audi rear muffler, gooped up the joint with the axle pipe using a pipe sealant and it takes.

But the front muffler to cat joint leaks like crazy (Volvo cat to Starla muffler) and even the Starla-Starla muffle to axle pipe spit out some of the joint sealant.

What gives with this Starla stuff?

Crappy fit, or is it me?

How do you get these joints to seal up?

(I even tried expanding the cat pipe going into the Starla muffler to tighten things. and cranked down on the Starls clamp way more than I should. No go)
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"Can't understand why people abort Volvos, either"