Here is something to consider: since our engines are higher compression, direct injection, a larger spark gap may not actually be the answer.
A dyno would give a better idea of what is going on but think of this: say a larger spark has a wider spark but still the same amount of energy released by the coil. A wide and thinner spark may seem to provide a better burn but it is also less stable. High rpm, high load at WOT and there is a chance you could still get spark blowout.
What you really want is the most spark energy throughout the entire powerband. I'm not totally sure how the ecu handles spark advancement/dwell and recharge or if they are all preset and static.
So in the end a smaller gap (stock 0.036~) may also be good for best overall performance/economy.
2012 SGM Ti DCT Stock and loving it
OEM multispoke 17" with stock rubber summer-X-ice 3's on stuck rims = awesomesauce