RE: Evolution 58GX - what RPM's should it turn?
Too bad - many people get led down the path on prop/muffler combos
Never try for an announced rpm - you will likely be disappointed. the 24x8 is a much better size as noted
On a proper large open can setup - the 24x10 will likely do the job -guessing
We ran tuned can of our own design on ZDZ60's -a lot -and they ran an honest 6400 at our elevation -on MenzS 24x10's
The MVVS is a fair match to this engine.
Hoped for and guessed at differences in muffler prop setups is a trap- and far too many people get caught in it
it is exactly the same as "30 miles per gallon" advertising -sure it CAN happen -but the actual parameters for it to happen are likely not the same as yours.