I'm beginning to find a rotton egg smell coming from my exhaust (convertors coming to end of their functional life), has anyone ever removed their cats and run successfully and trouble free without them? The car is a 1995 xj12, American emmisions.

 

You can run without them and not hurt the car. The bigger question is whether you will have the check engine light or be violating local laws. I'm not sure when your car would have been converted over to the OBDII engine management system, but if you have that, then removing the cats will garantee a CEL. If you have the older EEC-IV system, then you can get away without a light.

As for violating laws, I can almost garantee you will be doing this as all cars made after like 1988 (or something in that range) were mandated to have cats on them. Some states/locations have required vehicle inspections that must be done. Normally one of the things that they check for is if the cat is installed (atleast the body is). Getting caught (whether from an inspection or if a cop on the side of the road catches you) normally results in a pretty hefty fine.

You can do it, but be aware of the possible consequences.

 

i removed my down stream cats, no ck engine unless you do the upstream. you can have hiflo cats like magnaflo fabbed in for $100 ea plus labor, done to replace the upstream

 

Same for O5 XKR? Paramount offers "performance CATS" for $1700 UK dollars. Ouch. They claim 20 hp, but I'm skeptical of that much. I read somewhere on this forum that going to higher flowing headers can trigger rejection by the ECU.

They also informed me they could build ECU friendly headers of the XKR in the same price range that could be installed without pulling the motor. Think they're worth it? $3000 headers? I would guess a real pain to put in. And all that assuming that also didn't displease the ECU.

They were positive on every inquiry I made from anything from exhaust options to building a twin screw setup - but went silent when I asked via email about a Quaile unit in relation to the XKR computers. That was the LAST remaining issue to having the killer Jag. Damn.

(I keep envisioning the movie "TRON" and the evil master ECU.)

 

Well, we dont do inspections anymore (Thank You Jesse Ventura), and I dont have to worry about getting pulled over and inspected...I'm 35 and kids dont drive Jag's up here. My issue was the computer.

I supose I could just install high flow cats...certainly cant hurt. I might even remove the down streams.

$3000.00 headers....not in this lifetime, I went to school to build engines with 1,700 HP (pro stocks), and even they dont have $3000.00 headers, maybe $1,200.00 or so.

 

all in all, thanx for the input everyone...keep it coming please!

 

I wouldnt spend that on headers. That kind of money would be better spent on a whipple and 10X the power return.
on the cats I built my own stainless exhaust from headers out, including these metal matrix cats
http://www.randomtechnology.com/products.html
and spin tech custom built muffler
the cats are about $180ea from Summitracing.com.
and can easily be fabbed in place of the stockers by any good fabricator/welder
I used stainless wire in my mig welder and cut and pieced prebent stainless pipe into a custom exhuast
the issue with the ecu and 02 sensors is this,
The downstream sensors job it to only monitor the cat efficiency. The ecu knows what goes in the cats, and the cat efficiency is determined by how clean as a % that the exit gases are( I dont know the % before the codes P0420, p0430 are tiggered). The old school and still works today, is to space the downstream 02's out of the pipe some with a spacer so it doesnt read as accurate and THINKS its cleaner than it is. there are also 02 simulators on the market that send the correct signal. If you have someone do a ecu tune many times(if theyre cracking the software and rewriting) they can essentially deleted those codes from ever even showing up. I have personally had 4 codes overwriten to never show on my Nissan, cat codes(Im no longer running cats), p0128(have a colder thermostat in), and p0300(cams make the ecu think the engine is randomly misfiring when idleing)
now think about this, a whipple 2.3litre compressor is $2400, plus a $4-500 drive unit. some custom parts made to bolt it on the engine and pulley and youll have way more power than headers and full custom exhaust would ever get you, and for the same ballpark $$$ wise