The PMDG product page for the J41 mentions:

MS FSX with Service Pack 2 installed

FSX Acceleration includes SP2, but I seem to remember statements by some that it could make a difference whether one has SP2 installed or Acceleration.I assume the product will work with both but wanted to confirm first.Cheers,Siggy

Hi,I installed the J41 on my FSX Acceleration pack.Everything works fine.Matt.

Thanks, Matt, appreciate the confirmation !Cheers,Siggy

In fact it requires Acceleration or SP2...