Well, I think mine will come off this spring them also!

My HG is next in line to be replaced.

 

If you remove the cats you will throw engine codes from the rear o2's sensing no change in the outgoing exhuast mixture.

You'll also have a serious backflow change if you run stright pipes, and a louder exhuast. Unless you change the exhuast cam timing and displacement to match the drop, you'll probably see a drop in torque a small bit... not to mention (and far more important) be putting some really nasty crap into the air, causing a really bad smell, and a saftey issue if you drive into a confined space ie. garage with the thing running.

 

I'm with Kodiak on this one. Cats aren't as big a performance factor as everyone thinks, especially on an engine that revs as little as ours. The converters of old were the equivalent of pounding your exhaust pipe flat with a hammer, but these newer systems with dual cats and proper design work well. The heat issue is certainly a valid point, but overall I'm pro-converter.

 

There's also a software update for some of the beetles done at the dealership, but again, not for this car... We just lucked out there aren't any easy fixes for this one.

Yes, I'm still on JaguarForums.

 

I explained how not to get codes. I also left the stock mufflers on, so it isn't loud. You may lose one or two ft lbs of torque and gain 3-5hp. I've done this on a few cars including a 2002 BMW 330ci. That car got even larger hp gains and had no torque drop. This was supported by many members of a forum doing before and after dyno runs. This smell you guys talk about isn't even that noticeable. The average person would have no idea. And yes, it keeps temps lower and relieves backpressure on these poorly designed V8s, which were designed in the 60s (correct me if I'm wrong) when they had no catalytic converters. As far as polluting air, you got me there, but I rarely drive it anyway.

 

Someone on one of the other forums posted that his D1 still passed the sniffer test even without cats.... so I don't think the air pollution is as much of a concern as people are making it out to be.

Also having no cats would most likely REDUCE the rotten egg smell, not increase it. If you are talking about some other smell... I'm not sure what it is.

 

Well good to know. Yea, I never got why people were so put off by the smell. I was beginning to think I needed an olfactory tune.

 

They were initially designed in the 60's, but the current version is a long way from that between the 30% increase in displacement, fuel injection and distributer-less ignition. Regarding passing emissions, my sate has done away with the dyno and sniffer routine and relies only on the data from the OBDII. They don't confirm that the cats are even there. If you have no codes, you pass.

As for the rotten egg smell, that's hydrogen sulfide which is produced when the vehicle is dumping too much fuel into the engine. The excess fuel makes the converter run hot and process more material than it is designed for. Usually there is a code associated with this smell. It also will cook your cats.

 

I will probably leave my cats on until they give me grief (might be soon since have a 107,000 miles clocked) and then they will be removed to save myself some money. As I said before, the province I am in does not have emission controls so all is well!

 

I should clarify, my cats are falling apart, I am getting the knocking when hot sound out of them now.
With 221,000 miles on them they probably are not doing much anyway, so they are going to go and I am not going to replace them.
Yes you should replace them, but I am choosing not to.