Installing these beauties... Velocity AP Hi Flow 200 cells cats.

 

Be careful. I see you're in Los Angeles, like me. Beware of the Gestapo when it comes to Smog Check time. I had some 200 cell cats on my old XJ but got rid of the car before smog was due again, so I have no idea whether or not they would've passed. I kept the factory units in case I had to swap them back in.

 

All done and no check engine light yet. Pics show incomplete without final welds

 

How's it sound?

 

It sounds like a deeper raspier growl. No droning or excessively loud. Once my Exhaust finally comes in I’ll post a video.

 

It would have been interesting to have before and after dyno runs to quantify the HP gain from the 200 cel cats. Maybe you can do the "after" now, and the "before" when you have to put the OEM cats back on to meet the California smog test.

 

What’s with all the negativity? What makes you think that I’m taking the cats off? Did you assume this? I’ve got the smog covered. I wouldn’t have changed them if I didn’t have a back up plan. It may not be a XKR but it’s mine. I’m customizing it to my liking no one else’s. I’m not trying to race or beat anyone.

 

I wrote nothing negative and thought you'd have to reinstall the OEM cats based on what XJ8JR said. I know you think you understand what you thought I wrote but I'm not sure you realize that what you understood is not what I meant. I asked a fair question and you twisted my words in your head. Please read my post again and explain to me exactly what I wrote that was offensive to you. Your attack on me is unfounded.

 

Well, the dreaded Check Engine Light came on. Car is running great and sounds incredible. Time for a ECU tune...

 

Thanks for leading the charge on this pilgrim. We will all need cats one day and you are showing us the way.

P.s I can vouch for Stuart, great guy, doesnt have a condescending bone in his body. Not the type that thinks the rest of the world are fools (like some).

 

Thank you for the kind words brother. I found a company that will ship to CA. PM me for details

 

Where did they install the downstream o2's?

 

About 1 inch downstream of CATS

 

Bummer. I assume it coded for cat inefficiency?

 

I'll take a pic later....
codes: P0158 O2 circuit high voltage: (Bank 2, sensor 2)
p0491 Secondary Air Injector System ( Bank 1)
P0159 O2 Circuit Slow Response (Bank 2, Sensor 2)
P0139 O2 Circuit Slow Response (Bank 1, Sensor 2)

 

You could try O2 extenders...that got rid of the CEL on my old XJ. Not sure how it affects fueling though.

Do you have the 4.2 or 5.0? Have you noticed any change in throttle response or in the power band? When I installed sports cats on my old 4.2, I noticed a lot more power in the mid-upper range but I was never sure if the power band just got moved up a notch instead of actually adding power. I always had the sneaking suspicion that my throttle response and low-end torque had decreased a bit.

 

I have the 4.2 NA engine. I originally had the O2 extenders on there. It still gave me the CEL. I was told to take them off because it would screw up my Air Fuel mixture. I removed them and the dreaded CEL came back on within 20 of driving.

 

I also noticed my MPG went to crap. From 18 mpg to 11.6 mpg after removing the O2 extenders... hopefully the Tune will address this.

 

Our cars with 4.2 engines will loose torque with opening up exhaust, especially with the high flow cats. Tune to address this is a must, as well as the Cel light

 

Thanks, Q&C. I'm still waiting for the OP to respond to my Post #8, above, in which I stated: "Please read my post again and explain to me exactly what I wrote that was offensive to you. Your attack on me is unfounded." No response tells me that I would be wasting my time to be condescending to someone who doesn't get it.

Yes, you're right - he is the pilgrim who is leading the charge to show us the way. LMAO! His problems so far tell me that those 200 cell cats are the wrong way! They'll work, eventually, given enough of his time and his money.