I’m wondering can you use after market 350z pulleys on a maxima? Some colored and light weight motor accessories

 

If you want to free-up some weight, the biggest bang-for-your-buck is gonna be reducing unsprung weight on the car. Start THERE, because "most" everything after that is diminishing returns....generally speaking, it's like bailing out the ocean with a bucket.

 

If you are ok with harming your engine, yes, you can.

 

No, belt system is different.