tbh, I feel like k04 makes great power. but it's the power band thats the problem.
shouldn't the turbine housing be the upgrade? not other things?
or am i wrong about how that works
You are correct that for hardware tuning the power band the housing size is best way to adjust, but with the EA113 you have little choice for k04 turbine housings as its part of the manifold, band aid is K16 wheels or clipping, this how most the 'big' names for EA113 turbos do it
I went with a stock inducer, larger exducer compressor as my A4 K03 compressor housing limited inducer size and 7+7 rather than 6+6. Low end surge is claimed to be a issue with stock K04, this was try work around that and found a 9 blade which 5% bigger exducer/inducer turbine to try and match the shaft speed to flow. Honestly for my power goal a standard K04 would have enough but I was machining the cover anyway and had a damaged k04 turbine housings that would needed welded and machined so larger wheel meant no welding just machining.
I still have not found the A/R or CM^2 of the K04-64 turbine housing however
