You will find that a prop driven engine will need a lot of mid-range torque top end numbers really mean nothing other then more heat and viberation.
To date the best pipes we have found for really improved mid-range have been the Greve's long pipes with the headers set at 11".
Dont get me wrong the KS-1090's make power but it's way peakie and to fly IMAC with them is tuff.
Mind you some of the peakieness can be removed by adjusting the header but then you lose some of the pipes power potinal and when compaired to the Greve's the 1090's are heavy.
We have a AI Extra with a DA-150 and Greves pipes pulling 5950 hot on a Mejzlik 32x10 Mind you thats after porting the engine.
prior to porting the engine we were getting 5750 to 5800 with still good mid-range.
So remember it's more then just top RPM numbers,It's a lil factor called TORQUE...
