ok im sorta new on the engine mod thing, whats the difference on a 4-1 header and 4-2-1 header? i heard that a 4-1 is more for racing. lemme know thanks

 

its the way the pipes flow. like 4 pipes into 1 = 4-1; 4 pipes to 2 pipes to 1 pipe = 4-2-1

 

well which one is better then??

 

that's pretty arguable. materials, welding, and collector size all make a big difference. it would really benefit you to look on honda-tech.com and hit the search button and type in "header" or something along those lines. or do a scan through the Tech forum there.

 

A 4-2-1 header will give a little bit better bottom end torque than a 4-1. Also a one peice welded design gives just a little bit better flow... more power.

 

in "general" .. 4-1 = better top end. 4-2-1 = better mid-range gains. so ive learned. but who knows.

 

http://www.nissanperformancemag.com/november02/nerds/
http://www.nissanperformancemag.com/december02/nerds/

There ya go. Read up.