Hi i have a 2003 max that has the 3 cats and tonight im gutting them all just wondering if i have to do the anti fouler extenders on all 3 or just the main cat i have read MULTIPLE threads but cant find a defiinitive answer. if anybody has this done and has a setup that works that would be great if you could let me know where you put the extenders
thanks!

 

you have an 03, which has 4 O2 sensors...2 in front of and 2 behind each pre-cat.

NONE behind the main cat.

If you do antifoulers, you only need them in the "behind each precat" sensor location.

Why are you gutting the main cat? Does your state do emissions testing?

 

thanks for the reply i am doing it because it is extremely clogged up im going to get a high flow cat in the near future but im getting all cats gutted for 100$ so im doing that in the mean time. and to answer your question about emissions yes massachusetts does emissions testing but with the obd 2 cars they plug into the port and do it from there there isnt a physical sensor reading from the exhaust as in recent years.

 

dont bother gutting the main cat, it will just smell and sound aweful, you will gain nothing.

Just do the pre-cats.

 

one more question can i get by with just using one of the anti foulers after each precat or am i going to have to stack them one on top of the other (extend them) to get them work?

 

thanks tuner ill take that into consideration

 

I don't mean to hijack the thread but I have a question along the same lines.

I'm currently installing OBX headers and have plans on moving my secondary O2 sensors behind the Fast Cat when it ships. Would it be okay to run for a couple weeks with the secondary O2 sensors removed? I understand I should just get a MIL and codes complaining about the secondaries, is this correct?

 

Yes or just get sims

 

Rebel it will be ok as long add your primary O2s are ok.

OP, there are 90 degree anti foulers you can buy that are way better