PMDG B1900D Express cruise

Hello,I will apologize now if this has been answered, but, I'm posting because an afternoon of searching, both here, and Google, has not given me the information I'm looking for.I own the PMDG B1900D, and have spent the last couple of weeks flying it. What I'm running into is this. When I level off at either FL200 or FL250, the aircraft will not approach it's listed cruise IAS. At FL200, the best speed I can get is 227 KIAS, and this also with the OVERSPEED message on (and, yes, the max needle is below my IAS needle). At FL250, I can barely eek out 206 KIAS (again, with OVERSPEED showing).I do not understand why I'm seeing performance so far below the stated specs. FWIW, I also have Mike Stone's B1900D, and his is performing below par, too (176 KIAS at FL250).I am flying out of KDEN, the alitimeter is calibrated to ATIS (though I know that doesn't matter at the atlitudes I'm flying at), and have tried both Summer and Winter seasons in the sim. I'm using FS2004 (FS9.1 patch applied). I also have applied the 1.1 update to the B1900D.I hope someone can help with this, as it has me going in loops (sorry for the pun.)Thanks!