all you have to do is think faster and fool your opponent for a few seconds and you can win or at least get a guns solution.
the most plausable way, and one i have used many times against MA spit5s is when you are lower and an easy target.
you let them bounce you and play dumb to about 600 yrds, or untill they startshooting with accuracy above 600 yrds. the reason its 600 not 1k is because at 600 yrds anyone who is bouncing a seemingly unsuspecting Pony in a spit5 will be 100 % commmited to turning with you for a shot and latching on your 6.......so....at about 600 yrds, break turn to the right and look backwards the whole time, as you start the turn reduce your power to minimum for a number of seconds and then increase it if he is sailing by your tail and switch to an opposite turn left wing down roll and add enough climb and rudder to avoid being shot. he will sail by, he is expecting you to be running and trying to keep as fast as possible, you use what ever angle he gives you to turn his speed against him. at the very center possition of this move you want to be looking directly up through your canopy at him 'a la TopGun'. at this point you decide if you have enough time to roll level again before shooting, or if you will be forced to pull the shot inverted, banked 90 degrees, or whatever situation you are in.. this very short film shows what i mean but the planes are different and it is a front angle attack with speed from higher altitude. The first turn is to the left and very swift you'll miss it if yu blink kind of thing, but without it it would be almost impposible to succede in getting guns on before the 109 gets out of reach again... this move is exactly the same for any plane match-up anyhow though and if you are not mergeing at this angle then you can turn when he is at 1.5k to line up for the angle it requires, and lose/retain speed as much as is required for the match up. zeke vs typh you wont need to lose much. P51 vs spitv you're gunna need to be dumping big time unless the spit is already going mach 0.7.
------->
http://www.freeroleentertainment.com/sweet_BnZ_reversal.ahf <-------
in this 40 seond clip we let a 109 come right at us without reacting and then at about 600 yrds break up to catch him off gaurd and hope your aim works. you only get one chance but you can increase that snapshot with good rudder peddals that i wish i had.

I realise this is a very different plane match but it shows what i consider to be the very best angle to be attacked from, high 10 or 11 o'clock with just enough excess speed to want to go right back up again, but just enough oppertunity for shooting us given to commit his angle of BnZ to coincide with our planned move.
the reason i say turn to the right in the pony is because i find it is easier to do the follwing left wing down half loop/roll bit using the engines torque as a stabalizer as you pull the hard Gs.
Another way would be the obivous E fighting. merge CO-E the spit will almost certainly snap right back over at you, and you leisurely take your time to climb far higher than he ever could. but that is not turning with him i agree.
another and more difficult way would be to fake commencing a rolling scissors fight be mergin very low and almost a flat turn, and then at some point make a steep dive with the power off....the spit will think you intend to run and chase at you full power.
There is of course the classic overshoot.
------->
http://www.freeroleentertainment.com/109_downs_spit9.ahf <-------
this 30 second clip shows not a pony unfortunately, but still something less suited to the job than a pony, a 190G6 being attacked by a high alt spitfire mkIX. you would think the spit would win but with a keen attention to your speed and your enemies you can surprise what looks like a sure kill into a painfull lesson. This spit9 attack our 6 at 430 mph and we are gooing around 350. The pilot simply expects us to run, try a break turn and keep running with as much speed as possible. the last thing he expected at this time was a break turn dumping over 150mph and using the vertical to force him outfront. admitedly the shot was 1 in 100 to make, but we we're on his six and not too much slower anyhow. he would have had one rope left in the bag before getting down and dirty, at which point he would have the upper hand again.
and finally, the main way to win anyfight is to be one step ahead of your enemy, i know when i get shot down alot that i am being out thunk not out performanced.
------->
http://www.freeroleentertainment.com/LA7_downs_zeke.ahf <-------
last 30 second clip, an la7 killing a zeke in a rolling scissors style turn fight. i edited the 5 mins of fight where the la7 worked from 1k below the zeke to 1k above, but where we start is a normal attacking run on a slower plane.
it might look like the enemy is just unskilled (this is simply not true with yonoi), but check out the speedometer the whole time we are attacking we are also losing speed. the zeke will often try very similar evasives to a spitfire so i think this is relative. He was expecting a fast attack and zoom climb, but we commited the la7 with abloutely no power beind those turns aside from small surges to help roll over. through out thinking the A6m we and made ourselves a few chances before losing or running.
its all in the mind and reflex. speed of descsion making.
its not easy but i think the pony could outfly the spit with equal pilots certainly. the spit is uber but a pilot is still a pilot.
offer one easy shot, look like a noob, then attack when they least expect it.
make the possitions you most feel vulnerable from and make them the time to launch your attack from. if you hate being BnZ, learn a trick and perfect it.
If you hate being outturned, learn the overshoot and stall fighting.
etc, etc.
it is not all about turning circles and stereotypes.
ManeTMP showed me the way when he slaughtered my spit5 in a P47d40 back almost 18 months ago now.
all he did was made himself look juicy, then attacked when i was certain of victory.
edit: frantically looking through 1000s of films for a good P51 demo killing a spit5, i know i have seen it doene one on one with two good sticks before.