i'm using the stock SiR header with the two O2 sensors right now..will i get any noticable gains from an aftermarket header? which headers are made exactly like the stock one (i had a custom exhaust built, and i want it to line up like it does right now). thanks for any help

 

I have a dc (99-00 si) and it lines up fine. it only has one spot for 02 sensor, so you gotta rig that **** up.

 

did you notice any hp gains over the stock exhaust manifold? any codes from running only one o2?

 

I have DC 4:1 on my B16 and I noticed an increase above 6k. I'm only runnin one O2 right now and I occasionally throw a code but it runs fine, a little rich though.

 

import builders modded JG header http://www.importbuilders.com more HP then any Hype R.