Well, I think that this has to be fixed in an upcoming patch.
Otherwise, they shouldn't write things like "Authentic sound set" since that's not accurate.

http://www.youtube.com/watch?v=T3wIlvLpvFg

Filmed very close to the captain's seat in terms of position and angle.

And a few other 707 cockpit take-off videos:

http://www.youtube.com/watch?v=w0R12VE2SOs&feature=related
http://www.youtube.com/watch?v=U4CelCa7uMQ&feature=related

It's impossible to not hear the difference IMO.