With Ls/vtec.. wich header design 4-1 or 4-2-1?
4-1 for high end... but powerband is between 4.5-7.8 RPM
I dont plan on revving past 8K.... so 4-2-1? But 4-2-1 is mostly for low and midrange. So which one?? Which do you guys use and whats the results?

 

Depends on where you need the power... Been looking at dyno charts for LS/Vtecs (considering the swap).... The low end torque is good, and for a regular street driver the 421 will give you much more useable torque and make the engine feel more powerful....

If you drive on the highway, a 4-1 will give you more useable power in the Vtec range.....

That's just from chart research....

 

i have a jdm 4-1 on my ls/vtec.