I would want to look at the fault/error codes, the fuel pressures for high and low, the mass air g/s, and boost. Lambda as well. For the fuel pressures and boost, I would look at both target and actual. All to simply confirm those are OK. Hesitation felt under full or near full load usually point to fueling pressures lacking, boost, or ignition. So with ignition, there's spark plugs and coils. What have you installed currently for coils and plugs? Genuine VW OEM or OEM replacements? Exactly which plugs are installed currently? Their gap?