Anybody know if I need this donut gasket for my ZZP 3" offroad bolt on downpipe?

http://www.3800performance.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=RT-RDG&Category_Code=ES_H&Product_Count=18

Or is that just for the Random Tech downpipe? I have the two gaskets it came with, should be all I need, right? Thanks alot!

Normally you use the gaskets made specifically for the brand of downpipe. The one in your link is for the RT only. You should have two gaskets. The front and rear. Manifold flange to DP gasket and the one to the resonator flange.

When in doubt best thing to do is contact ZZP support.