Most recent update from the machine shop. Here are the stock N54 cylinder head numbers followed by numbers with only work in the bowl, and then additional work with larger exhaust valves. Numbers are VERY exciting. There is 35+% more flow on the intake side and 13.5% on the exhaust side.
Shop is working with Ferrea to get custom +1mm oversized Super Alloy valves capable of supporting sustained high temperatures on the exhaust side. One of my stock exhaust valves has been shipped out along with the spring and retainer and we are expecting word from Ferrea on the recommended way to go this week.