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halo guys,i wanna asking about the extractor (exhaust manifold)

i driving a satria 1.3 card,some people say a aftermarket performance extractor a part from 4-1 that piping,normal short is more better aftermarket long 1,cos gas run out to a point when 4 - 1 fast back pressure,aftermarket too long,back pressure to low respon.

which 1 right? izzit really truth just dun touch 4-1 part,just from 4 to 1 piping there weld it long more,got effect woh!!

if i wanna follow a size long normal 4-1...