Exhaust flex joints
 

If you remove the flex joint in front of the center cat, is it a good idea to offer some flexibility elsewhere? I replaced my center cat with an aftermarket cat and I am getting a resonant buzz between 3000 and 3500 rpm. Could the lack of flexibility be contributing? I was thinking of using those braided stainless flex couplers in front. Any thoughts?

Stephen

When I built my first exaust I didn't have any flex points in it and I didn't have any problems. However it would seam that after a wile of working it, it would fatige the metal and break somewhere. If you have an easy place to install a flex joint then you should do it althoe I don't think it has any thing to do with your noise.

Have you tracked down the source of the noise? My guess would be that its the heat shielding around the primary exhaust pipes. Maybe just a little readjustment of the heat shielding would be necessary?

Actually the car contains no heat shields, other than the integral one on the new center cat. Which is probably the culprit. It has straight pipes from the manifolds back to the center cat. It really sounds great, except for that dang buzz.

That darn cat
 

Actually, I should say that I do have the heat shields on the manifolds. Anyway, the new cat had a few spot welds that let go so I welded it all the way around the perimeter and now most of the noise is gone. I may end up just removing the heat shield altogether if it keeps bugging me, which it probably will.

Stephen