A couple more notes about the modified endcap:
I cut out the snorkel with a dremel and initially left about 1/4" (6mm) of it attached to the endcap. Started it this way and revved it up, but it didn't sound that great. The sound was maybe a little "harsh" or "metallic" or "square" (if any of that makes sense). Took the endcap back off and removed the last bit of pipe. I also opened it up just a bit and radiused the inside of the opening. It now sounds more "full" or "round" or, you know, better.
I'm hoping to feel some difference in power after this modification. It has always had great power, but the top end felt a bit choked. I ported the head a little during the rebuild, but that didn't change the choked feeling up top at all. I think the exhaust must be the culprit.