whats the difference between a 4-1 header and a 4-2-1 header
any HP difference. And is DC sports headers any good?

 

4-2-1 gives more power in the midrange. 4-1 is all up top. My engine is usually at high rpm when I'm racing, so I didn't see the point of the 4-2-1. I have a DC 4-1 SS, and I've been very happy with it for the price. I didn't want to spend the money on the JDM 4-1 at the time, and I didn't want to mess with something that wasn't just going to bolt on. I might get the JDM 4-1 and a test pipe before too long. The DC 4-1 gave very noticeable gains above 6k rpm.

 

I have the DC JDM 4-1, the header, is of a much better design, than the older model, Mine is heat wraped which help with the tinny sound normally accompanied with the DC's.

 

what about ceramic or stainless steal is there any difference between
two?

 

ceramic wont last as long as stainless steel. I beleive stainless will outlive your car and maybe even you.

Stainless generates more heat than ceramic. Stainless also looks better. IMO get stainless steel.

 

Agreed. Ceramic headers have cracking issues since the metal underneath is not very high quality. Get the SS. It's worth the slight cost increase.