which are good for which RPM not really a matter la... just make sure wat the future mod will u b done, then only decide the 4-1 or 4-2-1....
not many mech really know how to do the 4-1 that got all the pros setup in here... even they know, they oso won't share 1...
who said 4-1's torq must b lower than 4-2-1..??
yalah, didnt say it " Must " be lower la, thats y i specifically stated " In General " meaning not all :P, in all my comments
e.g. in general, most aftermarket 4-1 headers are more for mid to higher rpm improvement
true true about the properly made headers, unless branded jap-made, or reputable local ones like PZ
4-2-1 low to mid?
4-1 mid to high end?
How much rpm is consider hi rpm?
how bout if engine rev limit is 9k which is suitable?
if i recall correctly, i came across this interesting article where they tested a 4-2-1 and a 4-1 header on the same engine; powerband was broader, improvement throughout rpm range, more obvious on the low to mid range
then they swapped the 4-1 in; powerband became narrower/peaky, improvement mainly came from higher rpm regions
what engine u using? 9k considered high la