An inline 6 is impossible to cool when supercharged or turbo charged. There's no way to get sufficient cooling to the last two cylinder to evacuate heat fast enough. That's why Dinan's tune for the N54 and N55 specifically address this by increasing water pump speed FIRST. During testing they found that even at moderate increase in boost, cylinder 5 and 6 were showing signs of hot-spotting. The problem isn't solvable without significant investment into multiple cooling cores for oil and a MASSIVE radiator. I would be surprised if the new M3 does not come with at least 4 oil coolers and some form of upgraded water pump and radiator, if it does come in a tri-turbo inline 6. And I would be surprised if the 335 does not continue to suffer from limp mode induced by insufficient cooling.
The turbo charged 4, on the other hand...should be far more efficient in that regard.
The hell I don't! LISTEN, KID! I've been hearing that crap ever since I was at UCLA. I'm out there busting my buns every night! Tell your old man to drag Walton and Lanier up and down the court for 48 minutes!