I am getting a 4L60E built here in Aus and asked them to use the same spec parts as the sponsors Level 3 builds. Most bulders here are stating that 4 pinion planets are stronger than 5s, doesn't make sense to me.

Is there any basis to their statements?

I was told that the 5 pinion planets arent a complete necessity and are mainly needed in applications where towing will be done.

i dunno but i went 5

5 pinion planets have a little more surface area for load in the pinion area, However from what I have seen the area most likley to fail under performance stress are the splines in the center and they do not appear any stronger in that area, I can tell you that if you do use them get only OEM GM 5 PINION PLANETS. Not the aftermarket cheapys

yea in my case I went 4L65E front 5 pinion planetary.

I agree with Performabuilt. The GM powdered metal planets are the best right now. The aftermarket units are not as strong, but are less exspensive. You pay for what you get.