Quote Originally Posted by Lucas_R View Post
I dont think it would be wastegate related - but could be wrong. I guess its possible that its overboosting and hitting a boost cut that is programmed into the ECU software. Save yourself $6k and just get a new wastegate actuator if yours has play in it. $7k to replace the turbo is an insane amount of money - you could replace the turbo and get stage 2 parts for $7k.

06K145725T - IS38 Electronic Waste Gate Actuator - Audi 8V S3 & VW Golf MK7R– VAGPARTS Australia

It definitely looks ECU/TCU related as it drops off suddenly and significantly. Its certainly hitting a limiter at 450ish nm of torque and just falling off a cliff.

I would not be taking a modified car (or even a stock car) to VW for this kind of diagnosis, looks like you are in Sydney and there are dozens of independent VW specialist mechanic shops down there. Might be a good idea to start with the workshop that did the ECU tune and get them to do some logs and discuss with Galano - or possibly reach out to Galano yourself with your logs and feedback to see what they say.
Unfortunately Chris from Galano seems to be away for the time being - I've sent the data logs to my tuner who has sent them to Chris, but I have this three month dealer warranty (as I bought the car used) that expires in two weeks and not sure when I'll hear back. Hence if there's anything mechanically wrong with the car that could be causing this and it's not just a simple fix in software, I could save a lot of money fixing it now