I haven't drilled additional holes, it was so good with 2 coils I fired it could handle 4 fine. I just trashed those coils and switched to dual 28 awg microcoils with 6 wraps, hitting great, tons of vapor, and lots of flavor, at 0.32 ohms. Going to lose 1 wrap and see how it does.
There you go brother, I'd definitely suggest drilling some symmetrical airholes for your cap. Even if you like warm vapes because you can always do a few less wraps and make the coils hotter

. I'd also suggest getting some Gplat wire if you like the warmer vapes, it's totally made for the 28.5 Tobh trust me (Nichrome is nearly just as good too). It basically allows you to have double the wraps of kanthal, while still heating up just as fast, double the surface area, and you double the heat. To me, I always try to find the lowest ohms I can go (safely of course), paired with the largest airflow possible for the type of vape that I like. I love me some quad coils as well, but I simply don't have enough batteries to keep up with the power it uses

, soon I'll have enough to do octo builds if I want. But yeah if you have some coils that are heating up without airflow whatsoever, then your going to get juice/wick burning eventually, and a really "spitty" vape if that makes sense. You need that air to mix with the hot juice to make vapor period, it could actually work against you if you don't. I'd really suggest drilling at least 1 hole in front of the other 2 coils if you know that's all you vape normally, it'll only make more vapor afterall!

You can always build your coils lower to match the warmth that you want. (Btw I like vaping at .08 ohms, which is totally safe on a 50amp battery like the Sony, or Panasonic GCR, you'd be surprised at what they can handle safely.)
If you don't want to drill more holes, you can always center post both of the coils so that they are side by side in the middle, that might actually be better than a normal quad! Hope this helps brother, I recently drilled some "cyclone effect" style holes, and that made it so I could quad build without 4 air spots btw, you could try that too.