I am looking for a 4-2-1 2-piece stainless header for my stock B20 in my CRX. Which one is going to bolt up to the factory flange on the cat?

I have been looking at Greddy Headers but I am not sure why there are 3 different part numbers (I thought all B-series 1.8L Headers were the same):

ACU INTEGRA LS/RS 1994-99 4-2-1 1.8L 10551011
ACU INTEGRA LS/RS 1990-91 4-2-1 1.8L 10551012
ACU INTEGRA LS/RS 1992-93 4-2-1 1.8L 10551013

I am assuming the 90-91 Header is the one I want, can someone confirm? I search and couldn't find the answer. TIA

 

i think any will do fine but just to be sure get 90-93 thats what i had on mine

 

depends on where you want the o2 bung if you are obd0 get a 90-91 header, if you are obd1 get a 94^ header

 

Or just get 94 and Convert 2 obd1 anyway

 

I am already OBDI and want the O2 bung in the collector. So the flange orientation on the 94+ is the same then as the others?