Do you have to use the correct manifold for a pipe? or do you just change the tuned pipe when you wanna try a different exhaust?

What I mean really is, is the manifold part of the tuned system as a whole or is it unimportant is it just feeding the chamber of the pipe?


Or are Nova and Picco different for instance?

I have two nova pipes and one picco pipe and manifolds for each, I just want to buy the correct pipe for a new engine and I was wondering if I could use one of my existing manifolds and save some cash.