Hi, I recently replaced the turbo on my R56 MCS after close to two years of the old one being bad. Replaced with JCW turbo brand new and always added a high flow cat. At first it was making the "something in the radiator fan noise" (super knocking). Traced the problem to old coils. Replaced the coils and got rid of the super knocking but the problem that persists is that under heavy boost, it feels as though the DV is actuating on and off quickly and generally doesn't sound great either. CEL is on due to downpipe but no further codes.
Work done so far:
Carbon cleaning
HPFP
Catted downpipe
N20 spark plugs (NGK heat range 8)
New Coils
Timing chains 7k miles ago
Oil filter housing gaskets
Thermostat
Auxiliary Water pump
Throttle

Video of surging:

 

Check the wastegate arm length.

 

Hey thanks Neon. Upon gaining access to measure the wastegate linkage, I realized the pre-cat O2 was semi loose causing the issue. You can still write that up as a win. Thanks for your help

 

How is it running now? I am getting the turbo on my 2013 coop replaced as we speak.

 

Am I missing something in the video? I don't see it....

 

Turn the volume up. You can hear it going uh uh uh uh.

 

lol i like your translation of the sounds

 

Its running pretty good. Its hard not to be on the throttle when its been so long without the boosts powers