I don't think the M50 manifold conversion really adds any power - the only dynos you'll see are either from people who sell swap kits, or people who compared a stock engine/stock tune to m50 manifold/upgraded tune. You can pick up a few hp on a stock tune too, and if you compare a tuned stock manifold car to a m50 manifold car I doubt you'd see a real difference.

The M50 manifold doesn't even flow that much more area than the M54 manifold, to run an M50 you plug the secondary runners than have to port out the main ports by a volume that pretty much equals the plugged ports. And the M54 manifold benefits from the DISA system which you lose with that M50 manifold.

Yes, there are a lot of people who have done that swap and claim big gains and this or that, but there are a lot of people who will say or do anything to try to just justify the time spent on their mods; and many dyno operators willing to adjust a correction factor to put a smile on their client's face. Ultimately, there are many products marketed to enthusiasts simply because they are marketable - not because they actually offer any real benefit.


With that being said, this thread is about exhaust manifolds, not the intake manifold. M50 exhaust manifold do bolt up to the M54 head.