livesc400

I just had a true dual setup installed on my 1998 SC400. I eliminated the entire extremely restrictive "mid-section" of my stock exhaust. I added a new X-pipe in place of the Y-diverge from the two cats to the center resonator (this is where most of the restriction is). This exhaust was done with 2.25" piping all the way. Based on recommendations by JBrady (1999 LS400 and exhaust guru ), I used 2.25" so that I would not lose any low end torque. You may be able to get away with 2.5". The pipes went all the way to the rear muffler flanges so that I would be able to add axle back mufflers in the future. The huge rear resonators were also removed. My older 1993 SC400 had relatively small cylindrical resonator cannisters. My 1998 SC has freakin' kegs ...LOL. If you look at the this first pic, you can see just how restrictive the stock SC400 exhaust really is . The 1UZ-FE needed to breathe and I decided to help it out .


Here is is pic of the extremely restrictive stock exhaust. BAD BAD BAD

livesc400

Oh yeah....I kept the stock mufflers on the car for now to see how they would sound. The sound is definately like a V8 with no raspiness at all. I can't really describe the sound but it sounds great (Decently loud and significantly deeper rumble)!! It sounds very different than my 1993 SC400 with no cats. It sounds a lot more exotic. I guess I should say it sounds like a Toyota V8 . It's still quiet at highway speeds but you will defiantely be heard when taking off.

Here is the pic of the final exhaust setup(for now ). Notice there is MUCH less restriction than stock. The 1UZ is much happier now. It can now breathe

brendanlim

Well, my brother woke me up this morning. How? I heard him revving his exhaust outside, oh and he kept on asking me to come outside to check his car

The sound definately is deeper and throatier and I also did have a chance to drive it. Let's just say that I noticed a BIG difference driving his car.

Big ups bro!

Technics

It looks great man and should have released some tied up horses.

All we need now is a sound clip!!

livesc400

Thanks for the props Technics . I will try to get a sound clip for everyone or perhaps even a video soon.

NAZTY97

how'z the performance?? any significant noticeable differences?

SCV8

That's just got to help it to breath easier; the computer will sort it out after a couple days of driving and correct the mixture a bit, so you should notice another improvement then(if you haven't gotten there already).
I just did a similar thing to my '92; cut out the center section, ran two pipes from the down-pipes back to the tiny resonators, and put a very short crossover tube where the first "Y" used to be. It runs much better now,and I expect to see a one,maybe two mpg increase also.
I would like to hear the sound.

livesc400

Nazty97 - The performance was very noticable instantaneously. Like SCV8 said it may take a few days for the ECU to learn that it can breathe now . I will keep you posted. I wish I could have an official Dyno comparison. Judging by the seat of my pants dyno, I noticed quite a significant gain . It definately brings a big smile to my face. You can almost guess how much power is gained just by looking at the pictures and comparing difference in restriction. The flow of exhaust has pretty much been doubled. My best guess would be around 15-20 whp (conservative estimate). The Borla axle-back usually produces about 8 whp and this does not even touch where the major restriction is at (center resonator Y-diverge). The guy at the shop was like, "No wonder I couldn't hear it. It was breathing through a straw!" . I am planning to getting some Magnaflow street series mufflers after I replace my brake rotors/pads cuz the rotors are really warped.

Here's a pic of the "straw" my car had to breath through (after it was "chopped off"). Your cars' sections may look somewhat different but overall, it should be very similar.

nextlevelcoupe

iTrader: (1)

i wonder what the reason was for lexus to design this highly restrictive exhaust the way they did..

livesc400

My only guess is to quiet things down. My old 1993 SC400 dumping from the headers sounded extremely loud (like I heard you coming about 10 minutes ago ). It was still loud with the center resonator removed and rear resonators and mufflers in place. I know the 1UZ-FE block is made for a 500-600hp application. I guess they needed to silence this beast.

NAZTY97

here's a pic of my exhaust and it's not quite the same as yours,... wonder why.... only a year difference..??? Nevertherless,... it's the next mod in line...

livesc400

Depending on where you live, the emissions standards maybe different. Your setup is exactly like a car from Cali. You have a center cat vs. a resonator. Another thing is the difference in engines. The new VVT-i 1UZ-FE motor may have prompted Lexus to alter my exhaust design. Judging by your pic, there should be no problem with check engine lights if you remove the 3rd cat. As I mentioned before you have the cylindrical resonators in the rear. They also quiet things down a good bit. If I were you, I would either replace the 3rd cat with a 3" Y-pipe splitting into two 2.25" pipes or run a similar setup like mine. I think both produce noticable results. Good luck to you on your exhaust. Post some pics when you're done.

98LexSc400

livesc400

I am glad to see someone else modding a 98+ SC400. I have had my 98 since last august and have done a small amount of mods. Being that this is my daily driver and my Z28 gets all my extra cash. I still love to drive the Lexus and drive it hard. Only performance mod so far is a panel mounted K&N and removed air silencer. I had the chance to dyno mine when it was stock and I am also planning on doing some exhaust work very soon and it looks like your setup turned out nice. I am hoping to hear some sound clips of your exhaust if you can get them posted up that would be great.

machinegt

yesss sound clip neeeeed soundzzz!!!

livesc400

Sounds will be coming soon. Keep an eye out for the post. Maybe I can get my bro to film my car tomorrow.

Machinegt - I saw the exhaust tip in your signature and was wondering if you have performed any exhaust mods to your car. If so, what have you done? Just curious.