Ok Orion, here's some settings for you to try and see if it provides a workaround for the problem you're having.
Go to your Effects folder and edit the following 3 files:
fx_AfterBurnerFire1.fx
fx_AfterBurnerFire2.fx
fx_AfterBurnerFire3.fx
In fx_afterburnerfire1.fx got to the [Particle.3] section and replace the old X and Y Scale settings with some new settings, thus:
//X Scale=0.58, 0.58
//Y Scale=0.58, 0.58
X Scale=0.48, 0.48
Y Scale=0.48, 0.48
In fx_afterburnerfire2.fx go to the same [Particle.3] section and try the following replacements:
//X Scale=0.66, 0.66
//Y Scale=0.66, 0.66
X Scale=0.56, 0.56
Y Scale=0.56, 0.56
And finally in fx_afterburnerfire3.fx go to the same section and try:
//X Scale=0.74, 0.74
//Y Scale=0.74, 0.74
X Scale=0.64, 0.64
Y Scale=0.64, 0.64
These reduced scale parameters are just a starting point for you. You'll have to adjust them and then restart FSX each time to check how they look.
Basically, afterburnerfire1 is the effect at stages 1-2 of the afterburner throttle, afterburnerfire2 is on at stages 3-4, and afterburnerfire3 is stages 5-6. Hence you see that the scale of the effect gets slightly larger in each file as the exhaust aperture increases in size.
I hope this helps.
All the best,
Voodoo
Also, @Wingmate,
I've seen the effect you were talking about earlier. It happens at different camera ranges in the sim, where the effect can suddenly shift in position (temporarily only, I've found) to appear out of alignment with the aircraft (e.g. the burner flames appear outside the tailpipe). I've seen this now with effects on other models too. I've put it down to a bug with the way FSX handles camera viewpoints as distances change. Maybe its down to the way it handles the switch over to a different mipmap, maybe not, but whatever it is I don't see any way round that problem.