Theres a reason why almost every Mustang you see below 5k is usually running for its life.
Honestly there is nothing you can do, any decent 109 stick will stradle on you even in a merge and you are done with.
Even with a honest merge, co-alt 2k - you can neither outclimb, or out accelerate a 109, best you can hope is keep your speed
and just zoom on by and say No sir! Now if you have ALOT of E, you can grind the 109 down and perhaps hope he makes a genuine mistake
of blowing off to much E or in worse case scenario - reverse and give you a shot.
Best case scenario - hard-deck yourself at 5k cause once you have a 109k4 back there, best you can do is run and hope he
doesn't have wep for long.
I do believe both 51/109 are equal on wep on the deck, around 370ish maxed out, however
a P51 is faster without wep then a 109. Somewhere around 330 for 109 and 350 for p51.
However with 9 minutes of wep on a 109 don't think he probably all 9 minutes up, majority the p51's i run into
I hardly need the wep in combat since my climb, turn rate is enough to match a p51 without a problem.
Just remember if trying to out run a 109, might as well forget it actually - 109s outrun P51's clearly through 14k
with wep on.