If you're losing flavor with dual coils you probably have too much air flow. I'm not sure if the RM4 uses an AFC, but if so, try minimizing. If not, you could always buy some of that auto-repair cement to fill in the hole. Might look like hell but it would be functional. Better than letting it gather dust, if you ask me.
I started running dual coils over a year ago and I can't go back to singles. My current set up on my Tugboat V2 is a basic dual 5/6 wrap using 22G Nuke wire by Chadster, 3/32" ID. Meters in around 0.14Ω. My Mutation X is currently dual parallels, 5/6 wrap 24G Boom wire by Chaster, 7/64" ID, meters in around 0.10Ω.
By no means am I suggesting you try these builds. I'm just pointing out that I (read: exclusively) prefer dual coils over single coils.