Do downpipes deteriorate?

[Shawn Kubik]

This is a multi-part message in MIME format.
--
[ Picked text/plain from multipart/alternative ]
I thought my ping pang ting tang at idle and worse under throttle were due
to the hollow cat but now that I get it up on the lift I notice/see/feel any
leaks but the noise seems to surface in the downpipe just where it comes
down to 2 pieces, do they separate inside after awhile and start making
noise?



Also, I get some weird air-leak like noise from the shifter that changes
depending on how much throttle I have applied, sup with that?



This is a 91 80Q w/ 207k

--