what is the maximum power limit for this engine?
The max power output with the KO3 is about 280hp with supporting mods. On the other hand with a KO4 conversion 350hp is achievable. There's not much difference between the s3 engine (higher lift cams and stronger connecting rods) and the axx/bwa engine.
I know this is a year old but I believe that 270hp bone stock will cause big fueling problems in the mid range, the fuel pump (hpfp) is cam driven and without uprated internals the fuel pump won't be up to the job. Please correct me if I'm wrong.
250hp on a stock engine is widely accepted by bigger tuning companies.
Max power handling safely 350hp.