Size question

[ABDULLAH D AFGHAN]

Ok so Im finally ready to do my exhaust for 93 LS400, I got the parts today from Summit. I plan on sticking with 2" from cats to center resonator. Im replacing the Center muffer with a 2.5 Dynomax Bullet($39). I couldnt find a cheap good Ypipe so Im using the 2"in 2.5in" out from Magnaflow Ypipe($25) for the first Y and second Y. I couldnt find any hi flow resonators that were 2inch, ppl said Ebay but they only ones i could find were 2.25 from www.supremexhaust.com ($44 each)http://www.supremeexhaust.com/CategoryInfo.aspx?cid=66. Im replacing the mufflers with Magnaflow 2.25 ($66)
Ok here is my question. Is there anything wrong with starting out with 2inch piping from cats to the center resonator(Dynomax Bullet) and going to 2.25 resonator and mufflers for the rear? I mean is it going to hurt my performance or make it sound shitty or should I return the 2.25 resonators and mufflers n stick with 2" inch through out?

 

[JBrady]

You have actually posed several situations here.

First of all, good choice on the 2" pipe it will work well. That said the stock pipe is 1.97" already and mandrel bent stainless at that so there is no real reason to change the pipes from the cats.

Also, where the factory joins the 2 pipes into a single section they use a machine that stretches and forms each pipe into a D section. Personally, I would keep this section. Simply cut the single pipe off right after the 2 factory pipes merge. This is a better high velocity design than the Magnaflow "Y" you mention. The Magnaflow part is a one size fits all stamping and is not high velocity.

Now, the center single section is another concern. The only older LS400 (1990-1994) that I saw the exhaust on had a center catalyst with offset entry and exits. Does this sound like yours? If so replacing it for flow should work well and your 2.5" choice is good.

Speaking of cats the 1998-2000 LS400s and GS400s have metal substrate catalysts which are very high flow. Your earlier car probably has ceramic. There is some potential flow to be gained going with the metal core style catalysts which are available. Nothing critical but worth a thought especially if you are considering headers.

Now, splitting the center single pipe back into duals with the Magnaflow is not my first choice as its design is sub optimum and it is not high velocity. I would check with this company www.mazzurisuper.com as they used to offer Y pipes at a great price and may make you one if you request it.

Going with 2.25" in the rear should be fine. As for sound that is an unknown as every combination will have its own tone and until you try it you will not know.

 

[ABDULLAH D AFGHAN]

Is this what u mean?

Hey Jbrady thanks for everything. All the size I selected are advice that you gave me earlier this year and what I see you telling others. So Im going with ur advice. I drew up a pic below of what I understand ur saying, that you say its okay for me to go with 2.25 piping after the second Y?

 

[mshawari1]

If you are going to change your exhaust for better performance you should think about X pipe replacing alt two Y pipe you drew . if that is my car I will delete the two cat. and the small resonators and I will keep the size as 2.25 from the headers to the end (in my 1uz I have single 2.5" resonator only) … here is a picture for some Lexus with X pipe..​

 

[JBrady]

Hey Jbrady thanks for everything. All the size I selected are advice that you gave me earlier this year and what I see you telling others. So Im going with ur advice. I drew up a pic below of what I understand ur saying, that you say its okay for me to go with 2.25 piping after the second Y?

Abdulla,

From your post and your picture I am not sure you understand my previous post. Do NOT use the Magnaflow Y sections. They are not performance items. They only connect pipes they do not perform any tuning or scavenging.

Keep the stock front Y section. Cut AFTER the Y and add your 2.5" Dynomax Bullet. After the 2.5" section you need to split into duals and your 2.25 should be ok at that point. You could use the Magnaflow Y section at that point but would be better to get a true split and that is why I gave you the link to www.mazzurisuper.com

Keep us posted on what happens.

 

[ABDULLAH D AFGHAN]

Jbrady dont worry man I m listening to you on this the whole way. I m not gonna use the Magnaflow YPIPE. I will keep the front stock. After the Bullet, I am gonna use Mazuri Ypipe 2.5 Y into 2.25 and use 2.25 pipes and 2.25 resonators and 2.25 mufflers to finish it off. I will take lots of picks at exhaust shop and try to post the sound on youtube.
thank you for all your help.

 

[toyotasrfun]

re: size question, 7 inches on a cold day

 

[ABDULLAH D AFGHAN]

i called Mazzuri for the back half y pipe 2.5 y into 2.25. the guy was super nice n helpful but unfortunately they only do major sizes like 2in 2.5 3.0 and so on etc. So then I called Racing solutions-Columbia river mandrel bending and they said they can do it. He asked me if I wanted "Parallel" or "splayed", i had no idea so I asked him which is better and he said "Splayed" is better so I went that. should be here in a week

 

[jibbby]

Magnaflow also sells a 2 into 1 main center cat that flows extremely well.. The Y is high flowing and built into the cat itself and the gains were clearly noticed when I installed it on my SC400.... I got mine on Ebay for $75

 

[ABDULLAH D AFGHAN]

dual inlet cats? My understanding of Cats is Catatlytic Convertor and when i got under my car, I saw two of those. Both right after the Exhaust Manifolds. Another thing I noticed is that I have 4 O2 sensors(2 each side). There is two before the Cats and Two after the cats. The center muffler is like a round long muffler. Then there is a Y and it goes to these mufflers and then after that i tgoes into another pair of mufflers. I originally got the $25 Magnaflow Y pipes but i returned them both back to Summit. And ordered it from CRMB. I had also ordered Magnaflow 4x9 2.25 exhaust Mufflers and returned that for 5x9 mufflers. I am still waiting for those to arrive. Man one thing that pisses me off is when you order stuff and they take forever and dont give u tracking numbers. It makes u feel like they are scamming you. I went on the Meineke website (www.supremeexhaust.com) to get those "RESONATORS" and I ordered them and even got a confirmation email but then I checked and my card wasnt charged and when i replied to their email its came back as "No such email." I emailed Meineke.com and nothing. It pisses me off, i dont know if it was scam to get my credit card or what. Oh well I will probably have the parts hopefully by next week. Im going to LA this weekend to see my cuzin so Godwilling next week ill have pics n sounds. Gotta question for you, have ever raced 5.0 mustangs n Lt1 camaros with ur SC, and how did u do?

 

[jibbby]

Not sure Abdul if your question was directed to me...You asked if I've ever raced Mustangs and Camaros...I must ask you does the sun shine? Just kidding, yes I've raced both new and old...New Mustangs I found to be very fast, LT1 Camaro's are pretty quick too...I take them both under the Nitrous just barely...

Abdul it sounds like you are pissed off with your part ordering... Good luck, I found that if the company is legit and has been around for awhile it's usually not a scam to get your credit card... I wouldn't sweat it... Besides most credit card companies have your back, and will not charge you when your card has been compromised..Buyer protection has been my friend a few times in years past.....

 

[JBrady]

dual inlet cats? My understanding of Cats is Catatlytic Convertor and when i got under my car, I saw two of those. Both right after the Exhaust Manifolds. Another thing I noticed is that I have 4 O2 sensors(2 each side). There is two before the Cats and Two after the cats. The center muffler is like a round long muffler. Then there is a Y and it goes to these mufflers and then after that i tgoes into another pair of mufflers.

Lexus actually used a number of different systems. The SC has at least 2 different systems.

PLEASE REVIEW the following link for factory diagrams and test results on catalysts and more. This will help this discussion and understanding:

http://planetsoarer.com/cats/cats.htm

 

[ABDULLAH D AFGHAN]

pics of the parts

Ok Jbrady n Jibby i got most of the parts
The Dynomax Bullet 2.5inch
Y pipe 2.5 into 2.25
Magnaflow 12225 2.25 Straight thru mufflers
Let me know what you think of the Ypipe I had it ordered from Racing Solutions. It looks great to me.
Im still waiting on those 2.25 resonators.

 

[jibbby]

That will defenitely open things up for you Abdul...You should notice a nice differnce in power and sound...However, I must say good luck with the sound with those straight thru mufflers of yours, they have a tendency to scream under full throttle..

 

[ABDULLAH D AFGHAN]

well lets hope so. Its still not over. i gotta find some1 here who will do mandrel bends. I wanna get it right since i spent all this time n money. Im sure I can order the mandrel bends n just have an exhaust shop weld them on? right?

 

[JBrady]

The Y looks very good.

I am concerned about the bullet. Is the internal surface louvered or drilled perforations? Louvers are not good for flow and can create many problems. Take a closer picture of the internal pipe for me.

 

[ABDULLAH D AFGHAN]

pics of Dynomax bullet inside and magnaflow

Thanks, Jbrady, I m listening to you on this whole thing. I think you are thinking of a "GLASSPACK." I didnt know the difference between a resonator and a glasspack. I m guessing Glasspack has those louvers and resonators have those lil holes? I dont see anything but lil small holes inside, the same as my Magnaflow muffers. Anyhow I took pics of both, the Magnaflows and the DYNOMAX BULLET.

 

[JBrady]

Abdullah, good, you have the correct style.

As far as mandrel you can order stainless or mild steel mandrel pre-bent pipes and have your builder cut and weld them. You may get lucky and find a shop with a mandrel machine but that is rare.

For cutting and welding pipe I suggest that the installer actually expand (swage) the downstream pipe allowing the feed pipe to slide inside before welding. This is a very strong design and assures a clean transition. You always want the feed pipe slipped inside the downstream pipe. Most make clean cuts, align the 2 and weld. This works but requires much tighter tolerances to create a restriction free connection. The suggestion I am making is just like the way a pipe slides inside a muffer. Some actually slide pipe OVER the inlet of a muffler or connecting pipe and that is a lazy and poor way to create an exhaust system.

 

[ABDULLAH D AFGHAN]

Hello,
quick update. I got the Exhaust Installed at Meineke and decided to go with 2.25 crush bends. The exhaust is really quiet. But when you hit the gas its a really Low deep rumble and not loud onbnoxious. But in side the car its kinda loud. Performance wise I cant really tell. Here is a question, when I rev my Lexus as soon as let go of the acclerator the RPMS come down really fast to idle. But for example my honda when I REV it, the rpms wind down slower. Is there any reason for that?

 

[ABDULLAH D AFGHAN]

ok guys here is the update. i have included pix.