Asking for a friend who's machining titanium replacements.
I have a few guesses buy they are just that, guesses.
1 - the rod passes through the guts of the engine. The taper is necessary for either proper oil flow, avoid moving parts, or both.
2 - the taper is necessary for the o-ring oil seals to perform their job for reasons that make sense in my head but can't explain.
3 - weight savings
4 - the rod is a retrofit for preceding rod part numbers, and the taper is necessary for it to retrofit.
5 - I could do this all day, so I'm going to leave it to the people who actually know.
Thanks!
P. S: If you're interested in a Ti pushrod, let me know and I'll pass along his information. He'll also be manufacturing the end pieces, ala the STM part and the unfortunately discontinued Motowheels part.
I believe from my memory of looking at oil passages and flow through the engines that it narrows to allow oil flow from one part of the transmission to another.
