Hello chaps. I'd like to replace my cats soon seeing as I'm over 100k miles now. I'd prefer to swap in some 200 cell versions like the VAP ones. I did a search and there weren't a lot of hits. Has anyone replaced their old cats recently, either with new stock versions or 200 cell sport models? Does anybody have any tips on how to get around those pesky California restrictions or does anybody have a handle on CARB legal units?

 

I wouldn't bother if the vehicle still passes emissions. Catalytic converter efficiency is monitored by the engine management. Now what would make more sense is changing the 02 sensors, as they do tend to age and can lead to poor engine operation well before the vehicle fails emissions. However, I would wait another 5 years before doing that.

Do you have money you need to burn?

 

Agreed on the o2 sensors needing to be changed as well. Both high mileage cats and o2 sensors can degrade performance without actually sending up codes. I know from experience on my prior XJ. After 100k miles, factory cats will certainly be clogged to some degree, so new ones will restore some original power that's been lost. And 200 cell units will certainly add power with the appropriate mods and tunes. I guess I should've made my original intent clear...this is solely about hp.

 

Do they do a tail pipe sniffer or just plug into the OBD port?
With 200 cell cats a tail pipe test will probably fail you.
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No doubt 200 cell cats will fail but I'm ok with swapping in the stocks every two years like I did with my old XJ. Some places do just the obd port and some do the sniffer. It seems to be random in my experience.

 

Magnaflow makes some good quality universal cats that you can pick up on eBay for $100 each. Switching to 200 cell cats will throw codes unless you get a tune.