whats the differents in the 4-2-1 headers and the 4-1 headers......nevermind

 

I think that 4-1 piping goes directly from 4 pipes welded to one pipe, whereas 4-2-1 goes from 4 pipes to 2 pipes and then to 1 pipe. I'm not sure which would be better, because the rest seems to be all about how you want the air flow to be. I havn't seen any 4-1 exaust manifold piping...only 4-2-1

 

assuming this isn't a joke