I have found that electrical tape is not the best for this. Its flexibility often “self heals” any pin hole you make. You poke a hole w/a needle, & as you pull the needle back out, the tape snaps back into place sealing the hole right back up.
I’ve had better luck for this type of temporary test tuning w/cello (ie Scotch) tape. Once you pierce it, the hole stays open & consistent to the size of the needle. In other words, no closing up issues.
The other advantage of using a clear tape is that you can easily see the exact center of the stock vent. On the T2, the front vent hole is already incredibly small. Without clear tape, it’s near impossible to detect exactly where the stock vent is to be able to pierce a new hole exactly in the center. Using an opaque tape (masking, painters, electrical, or even micropore) is like covering up a dart board w/a bed sheet, & then trying to hit the bullseye w/a dart. You can’t see the bullseye.
I bring this up because you mentioned that you got absolutely no difference in measurements w/the hole poked vs not. I believe the above points are the reason that was the case, & I think if you redo the measurements using a clear piece of tape, you’ill see a difference.
It could also be that the hole was too big. As I mentioned, the vent hole on the T2 is incredibly small. Even w/the right tape, it would be very easy to pierce a new hole through tape that’s exactly the same size as the existing hole! I’ve done this myself on accident when tuning IEMs in the past. The trick is using the clear tape so you can see everything easily, as well as using a small & sharp needle (because you may only need to pierce the tape w/just the very tip of the needle).
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