Gutting the 1st Catalytic Converter for better flow in a 1999-00 NB?

[mx54life]

Hey guys this question pertains to our so called California edition 1999-00 NB who were blessed (or cursed) with two catalytic converters. To improve flow, I know some guys would retro fit the 01-05 exhaust manifold and disguise it with the heat shield, some would insist on an aftermarket header and sought the services of the so called "blind Smog technician".

My question is how about gutting the 1st Catalytic?

1. Will this increase flow?
2. Will this cause the ECU to throw a CEL?
3. Will this increase tail pipe readings?
4. Will this contribute to premature failure of the 2nd Catalytic Converter?

I understand all of the above mentioned are not legal but my goal here is to improve flow with out failing the tail pipe. I am aware that the Federal edition 1999-00 NB are not legal in California either so for as long as I will pass the exhaust gas readings my conscience is clear lol.
Thanks in advance.

[Greasemonkey2000]

1) I would think so.
2) l would think so.
3) l would think so.
4) I wouldn't think so.

Not very helpful i know.

[— kung fu jesus —]

1) Yes.

2) Definitely yes

3) Depends on the condition of your second cat.

4) Maybe.

I converted my CA 10ae using an '01 manifold. I had the cat and midpipe replaced when I did this so I could move the second O2 downstream. I had a 2.25" cat welded to a custom 2.25" midpipe. I didn't throw any codes and it really uncorked the flow quite a bit, and by that I mean considerably noticeable.

I had replaced the pre-cat (manifold cat) while still living in SOCAL. Soon after relocating to the east coast, it went bad again. So, I got about 2 years and around 20k miles on that expensive precat replacement. The 99-00s are really sensitive in the ignition (re: coilpacks). You can replace the cat(s), but a lot of times, weak coils are the culprit and foul the precat really fast.

After I retrofitted, I had no CELs. I didn't have to pass a sniffer test, but the car passed the plug-in OBD2 test with no issues. From the back, I couldn't discern any increased emissions by sight or smell.

[— kung fu jesus —]

http://mazdaroadster.net/showthread....758#post164758