I heard what sounded like a bad exhaust gasket and low and behold, I have a hole in one of my front cats.

So, instead of feeding the Lexus dealership and getting stock I have been exploring some options. Does anyone have knowledge of the Max-Flow aftermarket converters? They have em for about $160 for the LS and SC400 application, and I am trying to get a firm price on 'patterning' one for the GS. I am considering replacing both fronts with them for arond $300 plus labor.

Also, I have read in some searches that you should replace the O2 sensors when replacing the cats, true?

Lastly, since the O2 sensors all do about the same thing, do we need Lexus sensors? What about Bosch sensors or some such? I thought as long as the sensors are centered around the same readings and send compatible signals there shouldn't be an issue?

Thoughts?

Thanks!

NudderGS400

 

How many miles do you have on the GS? The cats are probably under warranty. The entire emissions system is under its own separate warranty. I STRONGLY doubt you gain any power using a stock cat over the factory and in fact could loose power.

02 sensors should be fine unless fouled or very high miles.

Other than stock sensors should work but you may need to modify their conncetions to work on a Lexus.

 

Well not sure of the casing but the cat itself is under lifetime warranty as per federal law. Now the GS may have metal substrate cats. Not sure. If so than you won't want to use anything but the OEM cat in there since metal substrate cats outflow any honeycomb cats (which are all the aftermarket cats on the market).

 

jbrady - I have right around 80K and it's a 98. Would end the conversation if they are under warranty, except for the O2 sensors. Should they be replaced? If under warranty, will they just replace one side (bank) and could that cause problems?

Guru - great info on the cat metallurgy, had no idea. Figured they said high flow and that was better (power wise).

Does anyone know if they are substrate type?

Thanks.

NudderGS400

 

If you take it off you'll be able to tell. Metal substrate have a wierd look to them and you can see through them. It's like a swirl or paisly configuration core (looking at it from the end). The honeycomb are just monolith bricks with standard square configuration. You'll pass out when you find out the cost of a metal car though. Aftermarket metal cats are available in Japan from Metalit and a few other manufacturers (all the cores are made by Emitec in Germany). They run about $500-$600. A core I can pick up for about $200-$300 but no coating on them. Just a core.

 

Nudder, the o2's are part of the emissions system and will be under that seperate warranty (to 100k ?) I don't know if the cats are metal substrate or monolith, let us know if you find out, SRT should definitely be able to say. It is very odd that yours failed. I notice you list the L-Tuned ECU. Was that dealer installed/approved? Could effect warranty if not.

As far as aftermarket claims of higher power... buyer beware... marketing and truth often diverge!

 

I am going to research the warranty first since this ends the issue, if they cover the cost, they can replace everything.

Thanks, good advice all around!

 

Hello Dan. How did the Lawrence Lexus install go. check yur PM
Paul

 

If I remember correctly, everything that has to do with the emissions is covered by 8yrs/80,000 miles warranty that is controlled by the law.

 

When I torched mine off the inside looked like a whole bunch of squares and you could see through it. I was told by a high performance shop that the OEM Cats are the best for the lexus as far as power output. Also you may have to move the 02 sensors unless you can find a cat the same size to fit off the manifold.

Or find someone to weld on a 2-2.5" pipe from flange to flange and tack-weld the OEM heat shields back on. Looks like you have cats yet you dont!

Oh it is illegal, and you will get an engine light so a 130.00 OBDII sensor at pepboys which can erase codes may be good.:eek:

If you want cats and more power just elliminate the first resinator and make a true dual exhaust to the 2 second resinators, even with cats I produced 30 more HP. Cost $40.00