RPM on engine run up

What a great DC3. I received my CD in New Zealand about 3-4 day's after the guy's in the US and I have enjoyed every monent of it.Fortunatly I am still flying full size DC3 down here so I was keen to check out the MAAM DC3 and beleive me it is very good.I have one question for Bill. In the static power check on the run up at the station barometric pressure(approx.30" HG) we normally achieve a RPM of approx. 2500 and in the MAAM DC3 I can only get about 1900 RPM. Our technical manual mentions a min. figure of 2425.From the data on the MAAM DC3 it would appear that both DC3s are fitted with the same engine/prop. combinations.Have I missed the obvious or can the RPM be tweaked up a little.Thanks again Bill for a great job from you and your team.Regards,Robert