Planning to upgrade the shocks and was wondering what is the diff from the Big Bore shocks vs the V2 ones? What should I get?

Also what spring and weight oil should I get?

I also heard a lot about different pistons, whats the difference between all of them? Which should I get?

Trying to get as much info because I plan on putting an order tomorrow since I need them ASAP.

All information provided is thanks for :P