I just wanna make sure that the 99/00 Si 4-2-1 header will fit the z6 head and then will it be the same mounting location for the 89 Civic Si Cat? Im looking into this header cause its more low end power compared to the 4-1 header...

Thanks

 

no. b series is different.

 

Sorry

Up here in Canada the SiR came with the B16a2 but we have a EK Si model so what would come after the d/x in US? and same question as above

 

ex would come after a dx in the us

 

Highest to lowest model, SI>EX>LX>DX.
but LX and DX are the same motor.