I'm currently updating the engine sounds for my existing sound packs, as I've found some better source files for a few of them (DB605 and P&W R-2800). Along with that, I've found that transposing the engine waves by +4 semitones fixes the slow engine sound issue.
And with all of this, I'm in the process of making FW-190 and Lavochkin packs. Keep in mind that the M-82 radial engine was basically a copy of the BMW 801, and sounds virtually identical. I'll be using the same Eng file for both, as AHII's sound system displays the engine sounds differently for each aircraft, making it sound as it should.