Thank you for yet another update. Few questions:
Is this smoke coming from the exhaust because the rapid/sudden throttle changes? If so, massive thumbs up!
Am I right in presuming that various exhaust colors shown here are dependent on the mixture settings (together with RPM of course)?
Glad you removed the overdone reflections on the fuselage.
EDIT: Doh! I just spotted the 'speedbar' in the lower left parts of the screenshots.