Can you please elaborate further? I assume you are talking about 6sp specifically, since 5 speed doesn't have a pass-through into the main transmission chamber. Even in 6 speed though, is the logic that tiny, microscopic bronze shavings may end up in transmission gears which also have brass/bronze alloy in it?

All OEM Shifters, and all Aftermarket shifters have slots to accept the guide pins mounted in the shifter turret housing. All OEM and all Aftermarket shifter bushing kits come with plastic bushings that fit the machined slots. Have you never bought a OEM bushing kit? I have done this like 5 times.

https://www.ebay.com/i/201599461994?rt=nc&_trkparms=aid%3D222007%26algo%3 DSIM.MBE%26ao%3D2%26asc%3D20160908110712%26meid%3D d052d285ec87400f849ed0ef43434fc3%26pid%3D100677%26 rk%3D2%26rkt%3D6%26sd%3D263743246314%26itm%3D20159 9461994

Well according to 5xracing, 99+ transmissions don't use this, but I swear my 99 oem shifter had them.

I have this and it has 2 guide bushings.
https://www.rspeed.net/Miata_Short_S...p/nb0-7000.htm

As I understand it, the concept is that a metal bushing will transmit user abuse to the shift forks far more effectively than a plastic bushing will.

I look at it the same way: ALL oem's use nylon. I have yet to see a shifter from a reputable/reliable OEM that uses metal bushings. They're not doing it to cut cost. They're doing it cause they want the components not to abuse one another. We're talking about really good transmissions in high end cars here, not just econoboxes.

I honestly never really understood why people go nuts over the super duper crazy bolt-action rifle shifter "feel". You can't shift it fast without constantly worrying about damaging something, and it's not like a healthy OEM miata shifter setup is sloppy in any shape of the word. And when it does get sloppy, you replace the two bushings for pennies and it's back to solid. I've used dozens of MR and OEM and personally prefer a fresh OEM setup every time. I know I'm the minority with that opinion so I usually keep it to myself.

Anyways, back on topic? :D
Free bump OP

That's possible.

I've switched from nylon to bronze. Material wise - bronze costs a lot more than nylon, that's already a good reason to use it for manufacturer. It also softens the feel a bit because plastic absorbs some of the shock, this improves the feel for street use. I'm happy so far with 5x one and plan on keeping it. I think slamming gears and not using clutch correctly causes way more stress and damage to transmission than a metal bushing.

it's more like the bronze bushing can get jammed iirc from posts I came across regarding issues with the metal bushings.