anyone know this extractor performance???
actually 4-2-1 and 4-1 make huge difference?
if your question in other interpretation means "is it worth it to buy 4-2-1 or 4-1 and worth every ringgit?". most not all, aftermarket extractors are stainless steel and they crack in time. they were meant for racing use on a modded engine, most of the jdm extractors are meant for track. if u plan to use it for drag then go the american way.
This is the "real life"
http://img261.imageshack.us/img261/4412/spoonhz6.jpg
Shiroi is right here. Heat wrap does crack you headers after a while. I've seen them crack in 6 months. If you don't want this to happen but cut down the heat in the engine bay, HPC coat it. Looks the parts and doesnt have any cracking problems. There's only slightly a bit more heat but the difference is to small to feel it.
On top of that, buy a better header as cheap ones tend to crack after a while