I haven't noticed mine ever slipping but the pully I believe is aluminum and for what it's worth, I don't think the belt fits very well. Rides to high.

Lucky.

My Mech came with steel.

Bought alt and it had a steel serpentine pulley.
Needed V belt application and bought from them.It is steel.
Did some reading about the single V belt limits and decided I needed a dual v belt pulley. Ordered through them. It's steel

Hey brad - how about the newer fet type isolators ? Doing some quick reading they have a much lower voltage drop and more efficient

For cables….Just ran into this site being linked / recommended by a few racers on yellowbullet. Seems like a good place.
https://www.batterycablesusa.com/bat...e-grade-tinned
Again, i’m sure there are many other decent places too.