Great website. I have been lingering for a while now and find the posts to be really informative. I did a search on the following, but came up short.

I observed a crack in my exhaust manifold (96 2.7L) through the heat shield. I picked up a stock replacement from toyotaworld.com with the appropriate gaskets and am planning on replacing it soon.

But....I got to thinking.

About a year ago the gaskets on both sides of the cat failed and were leaking. The flanges are a bit warped but with a some gasket sealer and retorquing they seemed to have held.

I am concerned that I have a restriction somewhere, or some other issue that caused the crack. Before I install the new part, I thought I would troubleshoot it a bit further.

I have not thrown any codes. The rig runs reasonably well, though a bit rough at idle (recently changed the cap and rotor which helped a lot).

Any suggestions are appreciated, even wise-ass ones about the rear end restriction. Thanks.

a cracked exhaust manifold seems to be a common ailment with the 2.7 motor, mines been cracked since i bought it used, almost a year ago, even tried to weld it, but it cracked immediatly after welding, anyways, i think it's just a weak spot, and some aftermarket manifolds claim to be stronger then factory, seen one offered for 100$$, maybe i should try it? hehe!
hth
Rick, Ore