Hi Guys-
I am running the OS 200 mounted about 45 deg. up from inverted and using a Perry VP-30 pump - stock muffler.
Fuel is Powermaster 15%nitro-20% Syn. Oil.
About 2 gallons of fuel max. run through it.
New OS F plug.
Cowl is shrouded to direct air over cylinder with at least 2x exit opening.
Tank is about 6in aft of carb.
For a prop I am using a APC 18-6W.

Question: All I am getting is 8000 rpms tops. Does this sound right? Just seems like it is not developing full power. I did not document it but swear I was getting closer to 9000 rpms when engine was newer.
I have spent a lot of time adjusting mixture and cannot lean it out any further.

Any suggestions on what I can try/look at to get more power?

Perhaps adjust the perry pump? If so, which way - more fuel or less?

Any help appreciated.

Ken