I am a newb when it comes to cars, I have friends who are mechanics who will help. I need to replace my cats so while I do this, I plan to upgrade the whole exhaust system one step at a time. I am looking to get a mean sound out of it (whether it will pass inspection or not is not my concern)

What I plan to do is leave out the resonator, and straight downpipe. I want to keep the dual exhaust and I want mufflers so it appears legal when I get pulled over


Please tell me in what order I would be able to do this where as I can not afford to upgrade it all at once.

 

I would suggest an "X" pipe straight back to your cats and then continue to your mufflers. As for order... I'd work on replacing your cats first (you can get hi-flo cats), then have an X pipe fabricated, then your piping made...

Jonny

 

I would go catless if you are not worried about inspection. I read somewhere that OEM cats are already high flow at high temperatures, not sure if I would bother with high flow cats.

Try to fabricate the exhaust with few bends as possible. Use an X pipe in the mid section as mentioned above, add mandrel bent pipes to sections where bending is needed. Go with stock 2.25 inch pipes if you are not going with forced induction. If you are stock motor and you go with larger diameter pipes, you will lose low end power.

IMO, exhaust gains are not noticeable and can be quiet pricey if you want it done correctly. I would save money and go with forced induction first time around. Definitely more bang for the buck as far as HP/dollar ratio is concerned.

 

Forget the X pipe. Save $100 for nothing.

I just CAREFULLY cut the center resonator, no it isn't a cat, and replaced it with a piece of exhaust pipe of the same diameter. The two banks merge in that resonator and they have a odd union. It seems that Lex went to a lot of trouble and I don't think it was without motive. I paid $25 to get that center pipe welded in and the sound is great. There is a louder "bark" when it starts. Just enuf that everyone knows it is a V8 but doesn't get the unwanted attention. And if you dn';t like it you have risked very little and can always remove more. With only the removal of that center res I got a significant reduction in back pressure butg it was pretty low to begin with.

John

 

I second John's opinion. I deleted the three cats, with straight 2.25 inch pipe, and deleted the 2 resonators, with the same size piping and kept the stock mufflers with tips. Love the sound and its not too loud, just perfect I my opinion and looks stock for my taste. Has a growl to it NOW!

 

I just cut the mufflers off and it sounded a bit better, more like a v8 euro car. I found a blow up of the lexus SC400 stock exhaust if you want it.

 

I'd say get an x-pipe...there's a reason why high end V8s and Nascar guys use them

 

Looking at the diagram, it says the center piece is a cat, not a resonator. Am I missing something, or just not reading this correctly?

 

it's interchangeable. some came with a 3rd cat, some came with a resonator.

 

This varies by year?
Also, how does one tell if they have a cat or resonator?

 

I second that? ^^^ Whats the difference between resonator and cats? I heard that it can make my check engine light come on and be bad for the motor if I take out the cats or resonator? is this true?

I plan on supercharging my stock engine for now until I can save for a 2jz engine and swap. will take a long time though at least a year .. can you supercharge the stock 1uz? or do I have to turbo/forced induction?

 

T,

The pic says it all. If you center unit looks like a piece of pipe then it is the resonator. Inside it is a smaller pipe that is heavily p-erforated and the space around the center pipe is filled with steel wool. It flows like the old Cherry Bomb.... which is to say restrictive. At least more so than a straight chamber.

Kay,

You are absolutely correcton every point. Its bang for the buck. I have seen dyno reports that proved a 11 HP gain and it was not an improvement across the board for a complete system redesign. For that money you could put in a new ECM chip.

That stock system is STAINLESS STEEL and should outlive all of us. That wool in my center section was still in tact with 150K miles on it.

john

 

My owners manual shows a picture of the exhaust, and says if its out of Cali, it has a third cat, due to restrictions of emissions. If it doesnt come out of Cali, then it has a resonator. Mine had a resonator, not a cat!. Mine was imported to Minnesota Lexus dealership originally then to Tom Williams Lexus in Birmingham, AL., I believe. Check the vin and double check or the original window sticker.

 

Lex, like everybody else is way into commonality as a cost cutting mfr practice. If they went to the trouble to design the center cat OUT then it must not have been a good idea.