I'd still take it that with a grain of salt werkes and these guys are USA based, and there are differences in USA model fuelling tables and ecu maps.
It's literally an open system straight through and short when you add the werkes, I'd still recommend a flash if your paying retail for a werkes pipe it's not that bad to pay for a obd tool and 25usd for ecutuner and flash a well documented map from here to it.