Cure for lazy Magnum...Has anyone built a Magnum for 7k+ revs?

So give us a rundown of you 5.9 like mileage, compression test, etc . Also what are all the items attached to the long block because this may be a tune issue. What have you tried? It could be mechanical, flat valve springs, worn rings, etc.

Yes, a 5.9 can be built to run and run really well. There are good flowing Mag heads, if you need them.