After doing some reading
here and
here, I'm tempted to put the stock resonator back on. I didn't suspect it did much, since it's located before the air filter, but the TLDR is that the stock resonator really does increase torque at 1300 and 2100RPM, and robs it at ~1700RPM. I do most of my driving at 1700RPM (~50mph), but also a significant amount of accelerating and a bit of driving at 1300RPM (~35mph). The snorkel that extends from the resonator to behind the radiator is most likely just to reduce engine noise, so it can stay off.
Seems to me that I really want power robbed (lower vacuum?) at 50mph and additional power at 35, so I'm going to play around with things a bit.
One thing I'm wondering though is how the T in the resonator works. Ideally, it would be engineered to draw warm air (straight through) at low air volumes, and cold air at high volumes. I haven't actually looked at where the 90° section of the T goes, but I can only assume it's simply drawing air from just in front of the driver wheel. If I cap it, I might mess up the tuning of the system.