1991LS400

How Many Catalytic Converters?

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How many catalytic converters does my 91 LS 400 have? Only two, right? Does the rear of the vehicle have catalytic converters also?

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Thanks. When adding two new catalytic converters what else should I replace and what things should I watch for? Should I get a whole new catback exhaust system, O2 sensors (how many), things of that sort. Any help will be appreciated.

P.S. Lextreme and I think cureline both said that the stock catalytic converters and the way it was kinked to fit the catback exhaust system was not good...er...something like that. Do any of you guys have any idea what I'm talking about? What should I do? If I get a brand new exhaust system it should be fine, right?

Thanks guys!

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Lextreme and I think cureline both said that the stock catalytic converters and the way it was kinked to fit the catback exhaust system was not good...er...something like that. Do any of you guys have any idea what I'm talking about? What should I do? If I get a brand new exhaust system it should be fine, right?

well the Ls exhaust sytem is very restrictive, but i mean its a Luxury car, and all those silencers and cats and mufflers ect........are need to keep the 4L v8 quite..

cut all of those out and it will sound like a dadgum nascar (not really) :lol:

you can get by with removing 1 silencer on each and it will not change the sound of the vehicle.

but in all seriousness, it all just depends on what you are trying to do with the car,ie....just upgrade parts, make it a little more free flowing, or make it loud....... like i said above its a LEXUS and its a luxury car, not a hotrod but whatever floats your boat is cool with me. :D

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Lextreme and I think cureline both said that the stock catalytic converters and the way it was kinked to fit the catback exhaust system was not good...er...something like that. Do any of you guys have any idea what I'm talking about? What should I do? If I get a brand new exhaust system it should be fine, right?

well the Ls exhaust sytem is very restrictive, but i mean its a Luxury car, and all those silencers and cats and mufflers ect........are need to keep the 4L v8 quite..

cut all of those out and it will sound like a dadgum nascar (not really) :lol:

you can get by with removing 1 silencer on each and it will not change the sound of the vehicle.

but in all seriousness, it all just depends on what you are trying to do with the car,ie....just upgrade parts, make it a little more free flowing, or make it loud....... like i said above its a LEXUS and its a luxury car, not a hotrod but whatever floats your boat is cool with me. :D

I want it to be more freeflowing because I will be adding SOME performance parts to my Lexi, however, I don't want to sacrifice too much and make my car LOUD. I still want it to be silent, maybe a little "buzzing" from the muffler is ok, but other than that, no extreme loudness.

Well, since the LS OEM exhaust system restricts airflow what does that do to the car? If I get an aftermarket exhaust system that is more "straight" how will that help my car, or will it not help it?

P.S. All in all, I just want to get my car up to par as much as possible...PERFORMANCE wise...without sacrificing my Lexus that much. Any ideas on what I should do?

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Lextreme and I think cureline both said that the stock catalytic converters and the way it was kinked to fit the catback exhaust system was not good...er...something like that. Do any of you guys have any idea what I'm talking about? What should I do? If I get a brand new exhaust system it should be fine, right?

well the Ls exhaust sytem is very restrictive, but i mean its a Luxury car, and all those silencers and cats and mufflers ect........are need to keep the 4L v8 quite..

cut all of those out and it will sound like a dadgum nascar (not really) :lol:

you can get by with removing 1 silencer on each and it will not change the sound of the vehicle.

but in all seriousness, it all just depends on what you are trying to do with the car,ie....just upgrade parts, make it a little more free flowing, or make it loud....... like i said above its a LEXUS and its a luxury car, not a hotrod but whatever floats your boat is cool with me. :D

I want it to be more freeflowing because I will be adding SOME performance parts to my Lexi, however, I don't want to sacrifice too much and make my car LOUD. I still want it to be silent, maybe a little "buzzing" from the muffler is ok, but other than that, no extreme loudness.

Well, since the LS OEM exhaust system restricts airflow what does that do to the car? If I get an aftermarket exhaust system that is more "straight" how will that help my car, or will it not help it?

P.S. All in all, I just want to get my car up to par as much as possible...PERFORMANCE wise...without sacrificing my Lexus that much. Any ideas on what I should do?

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You have 2 cats and a resonator on the mid pipe that does double duty as a resonator/cat.

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Mine is 96, I can relate to 95 and 97 models. There are 2 resonators near the exhaust outlets. Whoever told you that it has 4 cats doesn't know what they were talking about.

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Thanks. When adding two new catalytic converters, what else should I replace and what things should I watch for? Should I get a whole new cat-back exhaust system, O2 sensors (how many), things of that sort? Any help will be appreciated. 

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Just 4 gaskets (2 each) (front and back of the cats). Before removing the bolts, spray the bolts with penetration liquid and leave them alone overnight.

There is no reason to replace the O2 sensors.

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