How bad can an exhaust leak be?
 

What sort of things can happen if you don't fix an exhaust leak? My friend's FD has one and he's tripping about it? Should he be really worried? I think it's comming from the downpipe/turbo area. Also, he might have one between the exhaust and cat.
any comments?

Bad. My friend's TII had an exhaust leak. Within a month, it had eaten two alternator belts, fried a bunch of sensors, and now the ECU is dead. We haven't been able to connect that directly, but you get the idea.

Fix the exhaust leak.

Let nothing go maintenance wise on an FD. Nothing.

It depends on the severity of the leak. I had one that was relatively small, caused by a slightly warped downpipe flange. But I worked on solving it until it was fixed.

EGTs are awful hot, and if leaking significantly it's a problem.

Dave