New Extractor

[leftfoot]

the firing order for most 4 cylinder engine is 1-3-4-2. and if ur using a 4-2-1 extractor, it will merge cylinder 1-4 & 3-2.

u cannot merge ur extractor collectors according to the firing order because the exhaust gas is gonna collide in the 1st Y collector.

that is true.. when 1 and 3 fires it generates a pulling effect on 4 and 2 thus creating vacuum and ease off the next firing.. it goes on and on.. and on. faster and faster as you up the revs