Nice and quick installation. Sadly, the downpipes are not going to help you very much. For sure will see some improvements, but not much. The reason you are disappointed is due to the fact that your DME is not calibrated to run those turbos. The turbo efficiency, turbo curve, volumetric efficiency, wastegate operation and much more are very different on a 550i vs alpina. The sad part is the fact that you can not fix that without a proper reflash and JB4 can not do anything to help it.
Turbo flow characteristic map. Top is 550, lower one is Alpina.
Part of wastegate function. Top is 550, lower one is Alpina.
