Hameed

I plan on doing a custom exhaust mod (for sound purposes only) on my 99 GS400.

From the catalytic convertors ( closer to the engine ) back to the Y-pipe - I plan to replace the Y-pipe with two Double X's like this pic shows -

What are the pro's and con's to removing the Y-pipe in my exhaust system? I know it is a catalytic convertor, so I would be losing that function. Are the other two catalytic convertors sufficient to pass a smog test?

I plan on doing this mod in the next week or so and will have sound clips of my exhaust (currently has the L-tuned mufflers) before and after this mod.

I will be getting rid of the resonators as well. Hopefully I will not regret this decision.

rominl

iTrader: (4)

i don't know about canada rules, but my friend is from vancouver and he said any alternation on the cats and you won't pass

Hameed

So I have no alternative but to keep that Y-pipe section..................?

rominl

iTrader: (4)

i don't know, not 100%, i just heard my friend said it. you should be able to get the info from smog station?

JBrady

Hameed,

First of all WHY are you doing this mod? From you posts in the header section you appear to be hesitant to spend money for minor power gains. In the case of this mod there may not be any gain at all and in fact a low end loss is possible.

All X and Y pipes are NOT the same. The system pictured is NOT ideal. What are you trying to accomplish?

The reason for an X or a Y pipe is to join 2 exhaust flows into one that decreases the chance of reversion and in some cases actually create a scavenging effect. The volume and contours of the pipes is important to maximize this effect. I would recommend copying the factory layout with or without cats with a slightly larger pipe size. 2.25" should work very nicely. For an idea on how an X pipe SHOULD look here are pictures from Burns Stainless who make the BEST available.

You can PM me if you wish to design a system for a specific reason and I will do my best to advise you.

Hameed

Hi Jbrady, thanks for responding to this thread!

Actually I just replied to the header thread and I am convinced about the value of the header mod, I just don't have the dough for it right now.

Let me explain what I am trying to accomplish with this double x-pipe mod.

I know I will not be gaining any power and I also realize I might lose some power on the low end (similar to the loss that the L-tuned mufflers mod did). I also think I will be splitting hairs regarding this power loss.

What I want to accomplish (at a low cost) is purely a cosmetic mod in terms of sound. I really like the nice agressive sound from the 5.0 liter DOHC Mustang engine. That's it - all I want to do is to make my GS400 sound more aggressive, but defnitely not rice or obnoxiously loud. Just a nice V8 growl without any drone.

This is a low cost mod as I bought these two X-pipes here http://www.exhaustproslinc.com/humaxpiass.html - the website appears to be temporarily down - but I bought the 2.25 inch aluminized ones ($30.00 each).

LMSGuy (CL member) recommended this approach to achieve my goal of a nice agressive growl. He said it will basically sound like an exotic V8 - similar to a Ferrari engine. Yes, I know I am being shallow in this mod as it is purely for the sound effect.

I wish I had $600.00 to spare for the header mod, but unfortunately, I just don't have that cash right now.

Mrbig

It won't add much if anything and may just give you a beefier sound out of the car !!!

Hameed

That is exactly what I am looking for - a beefier and more agressive sound. So long as it does that, there's nothing wrong with it doing "just that".

JBrady

Honestly, I have never heard a car with 2 X pipes. Removing the center resonator and replacing with a 2.25" X-pipe should make it slightly louder. It will also change the tone. It may actually help power if you are using a tube style X pipe. Please post a pic of your part. Adding another X pipe will not help power but will change the sound. How much and to what I do not know. Keep us posted. I would recommend carefully cutting your old parts so that you can re-install if you decide you aren't happy with the mod.

This mod will change your cars sound but will not make it sound like a Ford 5.0

SCV8

I had my local performance exhaust shop fab up a replacement section that went from just behind the cats back to the smaller dual resonators, with a very short H-pipe in the same location as the old, pinched-off Y union, removed the single resonator, and rear Y union too. The car does sound a bit like a Mustang now, a stock GT perhaps, and does run better, maybe 5-10 hp. It's hard to detect while just cruising at lower revs, but gets a growl under hard excelleration.
I am also on a budget, spent $60 doing this.
Also, I haven't either seen an extra X section added like the one in the picture, did you have a chance to listen to that car be able and tell a difference over just one X pipe?

BA_GS400

iTrader: (1)

can't wait to hear your sounds clips.

I think the only 'con' here is that you may lose a little low-end torque. Probably not even enough that you would notice because you'll be enjoying the new sound so much.

i think the only 'pro' here is exactly what you are looking for. Different sound.

I would like to straighten this out, because I think it's mildly important.
"nice agressive sound from the 5.0 liter DOHC "

I'm thinking you meant the 4.6 DOHC modular motor. The 5.0 liter is a different animal, different sound, etc. Our Lexus engine is closer to the 4.6 me thinks.

Lots of the guys on the 4.6mod motor boards use and like the X-pipe. The Bassani brand is pretty popular too. I have to admit that I haven't heard of using 2 of them back to back!

I've heard that the X-pipe will make the TONE of the exhaust slightly higher pitched, and you'll get that growl sound I think you want. I do not expect it to LOWER the tone of your exhaust......


sound clips!!

Hameed

Here's another picture:


What is a tube style X-pipe anyway?

Fisher503

two

Chigga

I'm going to Hameed's place tomorrow to check it out.

but why do people insists on bigger pipes= less lower end? it has been proven that backpressure is a myth regarding power curve both by aftermarket companies & SAE engineers, the only way a power curve can be modify is by the change of the header design and the affect on the hall effect in an engine. The only way I can see the effect from power loss on the GS with bigger pipes are the change of backpressure has alter the reading in theO2 sensor.

Hameed brought up the post regarding bigger muffler pipe on a GS400 and the car loss power at the lower end, I was fairly curious and asked one of my friend who's much more educated in that field than me, generally it is possible the O2 sensors reading could be alter with the change of the pipe size, since our OBDII ecus change fuel curve regarding the voltage outputs, by slowing down the velocity of burnt gas the O2 sensor may misread the engine being running lean and gives more fuel, which cause the power loss.

Mrbig

Try it out and let us know how it works out for you !!!