More details in the words of Terry@BMS below:
Hey guys, Had a chance to strap down our 2016 340i today for an hour of dyno tuning. Having done lots of runway testing last weekend at Shift Sector, including taking down a stock tune M4, I had a feeling the car was going to perform pretty well on the dyno. And was not disappointed.
The current setup is 100% stock except for a B58 JB4 BETA, BMS intake, and a BMS B58 water/meth kit. Exhaust is fully stock. Fuel was ~93 octane and meth mixture ~80%.
The BMS B58 water/meth kit has some additional parts not included in our normal kits including a PNP nozzle adapter, an EWG connector for the JB4, and some additional fittings.
With the EWG connector in place we're able to control as much boost as the turbo wants to make. But we've found power peaks out ~21psi, despite the turbo willingly making much more boost. Runs from 22-24psi at the same timing values all resulted in the same or less power. So we're probably approaching the stock turbo limits now. Maybe another 15-20whp ultimately in there with exhaust and other work.
Most impressive is how well it holds power to redline especially relative to previous turbo BMW motors like the N54 & notoriously weak top end N55. I'm pretty excited about this new motor.