M54 Ticking Noise - Catalytic Converters?

[Canadian_E53]

Hey everyone,


I just recently finished replacing the head gasket and time serting the M54 in my wifes E53. During the job I replaced the lifters as well. Everything back together and car runs great. I can't for life of me get rid of what I think is a ticking lifter noise.


I'm assuming it's the lifters because there was no ticking noise before the head gasket replacement. I've tried literally everything to quiet them down (lifter additive, oil replacement, lifter bleeding procedure (holding high rpms for several minutes), timing chain tensioner.


I'm now leaning towards it being the catalytic converters. I was poking around again with my stethoscope and it sounded like the ticking was loudest when I touched the tops of the exhaust manifolds and on the catalytic converters as well. When I was doing this job I had to bang off the studs of the catalytic converters. I believe I may have damaged them and now this is the source of my ticking. It would be very strange to me if this was the case as it really does sound like a lifter tick or rod knock...but hey who knows.


I'm going to decat the car and put some headers on it next in an attempt to resolve this ticking as i'm leaning towards it being bad cats.


Here is a video clip of the ticking noise:
https://www.youtube.com/shorts/Ja395cOJRfE



Thanks
Tyler