Pls, experience with aftermarket catalyst?
 

Hi all
Car is a 1992 300TE with 140kmiles. I installed an aftermarket stainless steel cat. Everything is fine, besides: the engine has become louder. I guess this is due to the different resonance characteristics of satinless steel vs the iron of the OE. Is there anything I can do about it? For example I have seen some tape that could be wrapped around the pipes. This tape is sold for thermal insulation, but it might help to reduce noise as well? Any (other) ideas? Any comment is highly appreciated!
Bruno