Me? Why me? Am I exhausted???
Yes, GFR is right, look at the photos. You'll see that the airflow over the side of the fuselage and the effects of the wing boundary air layer will shape the exhaust. Also some engines burn really dark and others leave lighter colors. Best to find every good photo that you can get a hold of.
Then you'll need to see if you can duplicate it.
Over to you Gamary, Jester, Supah, Baron et al.