Exhaust Y-Pipe/CAT for V8's

Duc Hunter

Duc Hunter

New member
I have an idea and have decided to see if a new part will help performance. I looked at my exhaust and noticed that the Y-Pipe is welded to the CAT. It looks horribly restrictive! Over the next few days, as I was pondering if an improvement could be made by designing a new Y-Pipe/CAT from an HP/Torque perspective I paid the ever increasing gas prices a few times. Then it hit me, on old V8
 
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curtis said:
I would be interested, but I wonder if this part would be the same for '05+ VVT-i V8's.
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Well I looked under and '06 today and ta part, along with the rest of the exhaust, looks the same as mine, so it should.
 
That's very interesting. I too wonder about a vvti v8 exhaust replacement mod. How long would this project take before your friend can test it then mass produce them.:cool:
 
toyota03 said:
How long would this project take before your friend can test it then mass produce them.:cool:
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well I think we will build the jig after he returns from SEMA, around November 4th. I do not anticipate it taking more than 3 hours to build the jig, so it should be all done and on the dyno within a few weeks.
 
Duc hunter would this high cat-back exhaust system cause any check engine light to come on or maybe even fail inspections?:awais:
 
toyota03 said:
Duc hunter would this high cat-back exhaust system cause any check engine light to come on or maybe even fail inspections?:awais:
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Remember guys this is early days so we have allot of unknowns. IT may not add any power, or increase MPG at all. It should not effect anything as there are no sensors after/in that CAT/Pipe. I have allot of experience doing this kind of stuff in CA, where SMOG is very tough. I would go no where near this if I cannot take it to any gas station and get it tested and have it pass.
 
If you want information on this mod, JUST ASK ME. I have already replace thed factory y-pipe/cat with a custom bolt in unit. So If I wanted to I can bolt the stock pipe back in. I have the factory exhust muffler, I just got rid of the resonator at the tip and turnd it to the side to eliminate hte sulfer smell inside.

sound change- yes
performance change- hell yes!
emision problem-NO

there are no sensors after the cat, so nothing would come up out of the ordinary during a smog check. there are two cats one on each header that realy do the work. the third cat is far from heat and wont do ass much as you would think. I will snap a pictuer tomorrow and post it up for all to see.

performance gain is large on the top end, did i see a drop on the bottom, NO. especially when the motor revs up faster during acceleration also.

Anyquestions, feal free to ask. Oh BTW, the two flanges before the Y are a funky special totyota flange, not something anyone will have on hand.
 
We were going to have the flanges for the headers custom made, I assumed they cannot be ordered. Is that what you found? Did you replace your stock cat wit a free flow on or just eliminate it all together? I am also curious if you have any other mods, like an exhaust or intake? Sounds like you left the stock one in place and just modified the tail pipe.

Also, thanks for the pics! They will help for sure!
 
Just found out that borla has fitted a performance exhaust for the 05 v8 4runners.:awais:Can you imagine the combination of the y-pipes and the performance exhaust. Maybe a Filter charge from KandN in the future. Weee!!!
 
yes i left the stock exhaust, I have a TRD drop in filtr, and an intake pipe (but i am too lazy to weld it and put it in), I will have the intake done soon since i also have a TRD supercharger coming. Before anyone dose anything, please just hold tight let me put some pictures up and see what you think.

the flanges I was lucky to get. My exhaust guy saves EVERYTHING, even bad cats off old toyotas. the flanges make of 190's cars like corrola or camery or tercel. It might be possible to order, i will find out.
 
well here is the pick. the y-pipe is a gineric 2-1. the out put of the Y is the same as stock pipe. the picture is deceiving

3406Ypipe.JPG
 
Well what's the good word RXvedub? Any noticeable gain in power, sound, drivability, etc? I'm curious why you said that output is the same as stock, and that it's deceiving.
 
i dont mean power out put i mean the physical Y-pipe out put. The gains are good well worth it. i thold you about sound but that might have been from the tail pipe being turned, sounds good. no affect on drivability.

like i said, worth it.

here is stock
3406ypipestock.JPG
 
I don't know if I am remembering right here, but it seems to me that the '04 V8 is different than the '05 V8. When I was putting on my MagnaFlow Catback it looked nothing like the pic RXvedub posted of stock. On the '05 V8's the exhaust comes out the headers, through the cats (one on each side) then through resonators (one small one on each side), then together under the frong passenger seat. After they come together they hit the intermediate pipe for about 16 inches then into the HUGE stock muffler, up over the rear axle, through one final resonator and out the back.

The stock picture that RXvedub posted looks like there is a resonator directly after the cats (which seem to be sitting alot lower than the '05's). The '05 cats are tucked way up in front of the fire wall almost right off the headers.

Again, I'm not sure if all this is correct cuz I'm trying to go by memory here, but that is what I recall. Just trying to provide some info on '05's.
 
the picture of the stock setup is from the front of the vehicle back, the pic of the custom Y-pipe is from the rear forward. that resonator you are seing is the third cat. on my 4runner ('04) the headers have a cat on each one (you can see the pasenger side cat in the stock picture, the driverside has a carry over pipe that comes to the pasenger side (flange seen coming from the right side in stock pic).
 
I remember when I had my Magnaflow muffler put in and the crusty old exhaust expert pointed to that "Y" right off the bat.
He said "we need to do something with that". I just had the muffler installed, resonator cut off and the turn out done. Didn't do anything with the "Y". But I'm thinking of it now, and with a high flow cat.
Looking back I should have got the Magnaflow muffler that had the two inlets and one outlet and got rid of the "Y" right then.

Question for RXvedub: Did you have the rotten egg smell and did this set-up help with that?
 
00328 said:
Looking back I should have got the Magnaflow muffler that had the two inlets and one outlet and got rid of the "Y" right then.

Question for RXvedub: Did you have the rotten egg smell and did this set-up help with that?
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this is what i was originaly going to do, the biggest magnaflow 2in 1out. but incase the car needed that third cat to pass emissions (not visual, actual sniffer part) i decided to go this rout and skip the lowd noise and possiple dronning inside the car.
 
Yeah, I didn't want mine loud either, I went with #12586 the 22" model. It has a nice little "growl" under acceleration. No highway drone at all. Just wish I went with the same size but 2 in and 1 out so I could have had the "Y" modified at the same time.
 
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