O.k. , you covered most of the "bottle neck" of the driver.., the original coils were , for sure , at the upper edge of their capabilities..! I used some like these , trying to minimalize the height of some drivers and at 3 Amps I could feel the smell of burning , coming out of them !To be sure that what you want to use are better just make a comparative measurement of resistance , for sure the bigger diameter of wire will give you lower resistance .Temperatures above 80 decrees celsius will decrease , in time , the self inductance of the material , so in tests , keep an eye at the temperature of the coils !
Because this inductance are storing the energy during the time "off" of the mosfet and give it back in the circuit during "on" , I should suggest you to DIY by using some bigger thoroids ( as bigger as the space inside will give you) , and copper wire , 0,7-1.0 mm , as many turns you can fit . The core material should be " 52 " , is very good and stable in time (the cover color is a light green + blue on a side ).
About the resistance , at the actual value (0.050 ) the power dissipated right now is about 1W , so , the actual size should be enough . Stacking some more in order to lower the resistance (0.033 as you assumed...) will result in increasing the dissipated power of the resulting resistance.., so is better !
I'm not sure that I was too clear in what I said , but is late and I'm very, very tired...sorry...