The larger gap you say "makes my engine run better" will only promote carbon tracking should the pressurized air to the mags fail at high altitude. Sparks want to jump where they can.  I would like mine to jump across the .016" to .019" iridium plated sparkplug gap and fire the six massive cylinders under turbo pressure.  That will insure that going fast will happen in the event of progressive failure or lack of magneto maintenance. How many of you have "done" the mags as your engine times get higher? precious few, I'll bet.  "Oh!, I have a bad mag check, let me see if I can burn it out with a lean mixture before takeoff..."  Sound familiar?  Won't work on these engines.
I have the Slick (Unison) O/H book, thank goodness, not to mention an expensive torquing screwdriver just for mags.
I have done a few pair of Slick 4300's and the are like any other and easier than some; ie: they get dirty inside and guess what that dust does?...it promotes carbon tracking.  Just add moisture and, voilla, sparks fly where they are not wanted.  Like across the HDPE gear face with its copper distributor arm trying to point the spark to the proper cylinder.  What happens to the Omic restance of air at high altitude?  You guessed it; it goes Way South and sparks can fly.  Under thirty-eight inch pressure do you want a small plug gap?  Why do the high altitude Lancairs have pressurized mags?...  The circle closes on the plug gap.  Sure, autos have larger gaps these days but cars don't visit twenty-nine thousand feet altitude either. Maybe it's a minor point but I won't go there.
WPD 1895740IA
ps: sounds like George should check in here.  He's done the testing, no doubt.