im not sure the diff of a 4-2-1 vs a 4-1. what will be the best
so far my mods are dc exaust, aem cold air , aem pulleys, spoon rad,
please help me with your opinions

 

You'll notice a lot of higher end companies only offer one variation of header and for the price difference versus say a DC they can be well worth it. I will not post my opinion of which is better because there will always be someone who disagrees.