headers

what would be better for over all performance out of a dc sports header for a integra gs-r motor? A 4-1 or a 4-2-1?

i would say 4-1

I think 4-2-1 is better because it have better flow. First from 4 pipe go on 2 pipes then 1, the reduction of number of pipes is less.
Instead from 1 to 4; the exhaust have to turn more.

4-1

421 headers will give you more mid range torque and power while 41 headers will give you more top end power.

4-2-1 gives better low and mid, 4-1 is great for top end, but if your car is lowered @ all it may get really banged up because it hangs lwer than a 4-2-1 design. I'd go with a 1 pc. header set up because as far as I can tell the only thing the 2 pc set up is good for is the added weight.