The 4-2-1 header is designed to make mid-range torque. The 4-1 header is designed to make power in the high rpm range, like 5000 rpm on up. On a internally stock motor like yours, you are better off to go with the 4-2-1. If you went with the 4-1 you would actually lose low end torque and the gains wouldnt start until your car was almost tached out.
Get the 4-2-1. And neuspeed makes good headers too. I would go with either neuspeed or DC.
