[Hiboost]

So are we talking 1-3 knock sum or like 10+ here?

Somehow I had a feeling that ditching the Garret Gt3076R turbo wasn't going to fix your knock issues.

I feel bad that you are having all these issues with your Evo X when it was a strong runner before you performed major mods like a turbo upgrade. So if you are getting knock is it possible that your injectors aren't delivering the fuel evenly? Was the car tuned on the injectors before the turbo swaps and if not can you swap back to the stock injectors and see if there is any difference? I still think a good fuel pump is worth getting installed sooner than later, even if your AFR's are rich and safe now. Once you resolve these issues you will be limited to lower boost or risk leaning out without control down the road.

If compression is the same across all 4 and air entering the engine is even, fuel delivery seems to be the only other variable that could cause knock. You might be 10.3 AFR's in 3 cylinders and 12.5 AFR in another for a combined 10.8 on your wide band which is reading the average from all 4 cylinders downstream of the turbo. I know if all the plugs seem evenly colored with no signs of detonation that possibility seems remote but you literally have to do a WOT run and turn off the engine within 30 seconds in order to read the plugs accurately.

With the bigger turbos the spark plug gap can't be too large or it will blow out at higher boost. Likely this isn't your issue though but something to keep in mind as I had hesitation with zero related knock from having gaps too wide. Perhaps your ignition coils need a looking at, but I'm not sure if a lack of spark would cause knock.

Possibly the timing chain on the cams is off a tooth?

I'll let others comment further on what else it could be but those are a few things I could think of off the bat that aren't directly tuning related. Hopefully you'll get this sorted out soon!