Don't get me wrong I do understand your logic as I intended to do the same to my 2.8 and I did the manifold mod on my M52TU28.. But after weighing up what it would cost to get it upto M performance it was just cheaper to upgrade to an M...
From what I researched I think the only way to get the most from your 2.8 would be to fit a supercharger .. But that's big money..
From what I researched I think the only way to get the most from your 2.8 would be to fit a supercharger .. But that's big money..