Secondary cat delete

[tmontague]

Hey guys,

I'm getting a custom exhaust installed early next week. The guy doing the work (trusted and knowledgeable) recommended a secondary cat and resonator delete with 2.5" piping and an aftermarket exhaust.

He stated I won't lose low end torue but will increase top end HP due to my other mods (intake header etc).

He also stated that my CEL wouldn't get triggered because the O2 sensor only reads after the first cat so the second one has no effect on a CEL being triggered.

Can someone please chime in on this. I don't want to go through the work and then have to re install my second cat due to a CEL. If the CEL will get triggered then I'll just do a resonator delete instead.

Thanks

[Jason@SportsCar]

2.5" is to big if you are running NA, you will lose tq, 2.25" is plenty big. I would not pull the cat on a road going car, if you want to make noise pull the resonator.

[tmontague]

Thanks Jason. The exhaust guy said he could do either 2.25 or 2.5 but he recommended 2.5. Will the secondary cat delete change the sound to you more deeper tone? I'm looking for performance as well as a deeper ton but not an obnoxious fart can noise that just sounds dumb.

If there is not CEL w/ a secondary cat delete then I have no prob with it. If I have a CEL then it become problematic for me. It makes sense that no CEL would be thrown since there is no O2 sensor after the secondary cat to trigger it.

[Rigaud]

I did 2.25, based on displacement and hp with an n/a engine. If you where recommended 2.5" don't do it and forget this guy. Jason's advice is spot on. I used a free flow 6" diameter muffler as a resonator and one free-flowing cat up front. The sound is deep not tin can. I already posted this several times elsewhere.

[tmontague]

What is the issue with removing the secondary cat (other than pollution)?

I searched the forums but never found your thread

[WeeYari]

I seem to recall some discussion from ages ago regarding pipe sizing. 2.25" if mandrel bent, up to 2.5" if crush bent.

[Rigaud]

Originally Posted by tmontague

What is the issue with removing the secondary cat (other than pollution)?

I searched the forums but never found your thread

No issue with one cat as long as your car has one and it's approved! I'll find the part numbers from my set up later this evening and PM you the info.

As for 2.5" crush bent....................NO, just no. You seem like a guy who wants to do things right!! ;)

[tmontague]

No this guy's stuff is all mandrel bent. At this point it's looking like i'm going to go 2.25" with the secondary cat and resonator delete with aftermarket muffler.

I'm going to ask him why he thinks it's worth getting rid of the secondary cat. He had briefly mentioned that it doesn't do a whole lot since the primary one is there. He also said it will just help with lowering the tone of the exhaust and allow for less restriction overall.

[Fluxtasy]

Hi all, I'm driving a Vios/Yaris sedan matic and just had the 2nd cat removed before the resonator and replaced with a piping of the same diameter. It does feel less restrictive and some lightness to the pedal.

I'm just wondering if there is any difference if I had the 1st cat delete instead of the 2nd cat?

[tmontague]

Performance wise, i'm not sure, maybe a slight difference. The stock cat are not very restrictive to begin with.

How ever w/ out the primary cat you'll throw a CEL and not come close to passing emissions (not sure if you have those or not). The primary cat does most of the emissions work as it gets very hot, the secondary not so much.

[Fluxtasy]

Testing is only required if I sell/transfer ownership of the car. No CEL from my 2nd cat delete.

The guy at the exhaust place told me I could remove both cats if I wish but since I'm running the stock muffler so the sound would be horrible (air rushing through a hollow tin can). Anyway I think he removed the 2nd cat as it is a easier job than removing the 1st cat. Just wondering if there would be any improvements if I had the 1st cat deleted instead of the 2nd.

[SirDigby]

wow. I've never looked at the exhaust system. what a bunch of garbage!

[WeeYari]

Originally Posted by SirDigby

wow. I've never looked at the exhaust system. what a bunch of garbage!

??


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[tmontague]

Finally got my exhaust complete! Picked it up last night and have driven about 150km on it so far.

I got the work done at Techtune in Etobicoke/TO. around 427/Gardener area. I was recommended to go there from my buddy who got his Jeep done there and his cousin who performance tunes/builds Mitsubishi Eclipses and currently owns an 800whp AWD eclipse he built himself that actually runs/races (true story). Bottom line, my recommendations were well sound.

I called JPG exhaust in Oakville first since they're closer to me and they had done simple fix up work on my Echo. Quoted $450 for SS and a simple resonator back exhaust. The guy was rushed on the phone and never offered any recommendations to me.

I called Techtune and the owner picked up. He gave me recommendations and even knew right away without me telling him that the Yaris had 2 cats and only the 1st one is used for emissions and has a downstream O2 sensor. He quoted me $250 for a full Primary cat back exhaust using aluminum. It would have been $400-$450 for SS.

When I got there around noon yesterday the owner was busy working on a car so I spoke with his assistant mechanic (a younger guy). The assistant did not know what the older guy told me on the phone the day before, all he knew is that I told him I spoke with the owner yesterday. He lifted up my Yaris and had me go under it with him and walk him through what I thought I wanted.

I told him I wanted 2.25" and he asked why I didn't want 2.5". I explained potential issues brought up on this forum regarding torque. I asked his opinion because I wanted to know what he thought and why he thought 2.5" was better than 2.25". Most of the info on this forum was here say and theoretical and the same with any other forums. I highly value and appreciate the experience and input on this forum, but I wanted to hear what Tech tune's reasoning was for going 2.5" and what their experience was in the real world.

Worst case scenario I could always switch back to 2.25" if needed. The assistant mechanic said that because I had an aftermarket header (he also asked/looked at the other engine mods I had done) it would create the restriction I needed for back pressure. He said the 2.5" would allow for the gases to expel better at very high rpm like on high way speed downshifts (which is where I felt the Yaris lags). So basically the header creates enough of the backpressure needed for the low end torque, but the 2.5" pipes allow for the top end clearing need for high rev power.

I weighed this with the advice on the forum and decided to opt for the 2.5". The whole time I spoke with the mechanics at Techtune they were always very confident and helpful, they never seemed to second guess themselves or act unsure. That being said they weren't pressing or judgmental if I wanted to do something different it just seemed like they were offering genuine advice.

Now I'm a 25 year old grad student who's getting married this summer and will likely have a baby in a year or two. I was looking for performance primarily but also wanted some noise when really throwing down the throttle. The stock exhaust is dead silent and I couldn't stand that. The last thing I wanted was a fart can that has a high pitched buzz throughout the whole rev range. I want to keep my Yaris somewhat classy and make it as much fun as possible. The mods I do on my car are for my own enjoyment, experience and learning not for others recognition.

The mechanics recommended to remove the 2nd cat and resonator and put on a turbo exhaust. They said if it's too loud then they'd just install the resonator back on for me for free, but recommended to try it without the resonator first.

The new exhaust is much louder than stock obviously but it's different than what I've heard in other 4 bangers around where I live. It has a rumble sort of like the Subie rumble. Now obviously not the same as the Subie rumble as nothing sounds that good ;) but I notice that if I rev it at idle it rumbles/burble's nicely. It doesn't get louder and louder as the revs climb either. I find it is actually louder if I try and low shift around 2,000rpm vs shifting at 3000rpm. It is initially loud when starting to accelerate but sort of settles in as the rpm's climb.

If I drive on the highway under 3000rpm it sounds similar to stock. When I go above 3000rpm you can hear it. I don't find it annoying like a drone per say but it is louder than a typical quiet commuter car.

I haven't really noticed any torque loss yet. I still need more time driving the car though before I can confirm any changes. The Yaris pulls much better now around 5,000rpm and above. It no longer seems to plateau after 4500rpm it just pulls hard and you can hear the engine screaming now. The engine now finally has full flow of air in and out from the intake all the way down to the exhaust.

It's a shame you can't tune these cars but it is what it is and that's also what makes them last so long.

The exhaust tip looks clean out the back it is larger than stock and is a somewhat rounded square shape. I didn't pay extra for a larger one as I personally don't like the look of the massive oversize tips.

I chose aluminum as it fit my budget at the moment. I also didn't feel that almost double the price was worth it for SS. When the aluminum wears out I could always change the exhaust to something different if I wanted and it is relatively inexpensive. 5-7 years out of aluminum would be great I don't need 10+ years out of it if I'm only paying $250 for it. I drive my car often so the exhaust is constantly hot enough to dry out as well.

I will be putting my car on ramps later this week to take picstures and check what type of bends they used. My buddy told me that he was sure they did mandrel bends but I never actually asked the mechanic. I know they aren't the ripple type crush bends, but I'm not sure 100% if they are mandrel bent or not.

They also sprayed the exhaust with silver spray paint after wards which makes it look pretty nice.

I'm thinking I should paint the exhaust this weekend to help protect it longer, but I'm not sure how well that will actually help it. I have some high temp black paint left over so I may give it a go. We'll have to see. If anyone has any advice on that let me know.

All in all I'm damn pleased with the performance, sound and work done. I only paid $250 which I think is a great price and considering what i paid, I think it was well worth it. I likely could have sourced an exhaust place that had the highest grade SS and had full mandrel bends etc, but I would have paid well over what I was willing. I was more than pleased to pay their asking price for the work and was happy with what i was able to get done.

I would highly recommend Techtune's work. I hate taking my Yaris to mechanics as I only trust myself with my car, but I never once felt uncomfortable or untrusting of them. They know what they're doing and I can see why a lot of Porsche and Audi guys take their cars there. If you live in the area I'd seriously consider some sort of aftermarket exhaust from them.

Before I left after dropping my car off I mentioned if they could keep the stock parts they remove in case I ever need it back to stock. They said no problem. When I picked up my car outside their shop hours after they closed, the removed pieces (bolts and all) were all placed neatly in the trunk and they even put a garbage bag down so it didn't dirty anything up. That was nice to see, especially when the Toyota dealership a couple years ago decided my non oem floor mat wasn't safe when doing recall work and decided to just toss it on the back seat dirt and all...

I'll post pics and a sound clip up by this weekend. Fire away if you have any Q's

FWIW my fiancee can't stand high pitched fart cans but mentioned that she could hear me coming home from the street over last night. She mentioned that she doesn't find it annoying or high pitched but more or a loud burble that she said sounded nice.

[WeeYari]

I take it all new work is welded right in. No flanges?

[tmontague]

All welds except for a curved pipe going over the axle. It isn't a flange per say but a clamp.

So essentially from back to front you have muffler, u clmap, upside down u shaped pipe going over axle, u clamp and then long 2.5" pipe welded into primary cat.

Also there are other welds near the muffler so the actualy muffler is more to the front of the car than the stock one. So there is about 1-2' of pipe from the muffler to the tip. This aids in lowering lowering pitch.

I'm assuming this is due to being able to install it as a whole piece since the axle is in the way.

Everything else is welded

[WeeYari]

Can't recall if sedan and hatch share the same components forward of the axle. I have a hole in my resonator and would be willing to buy yours if you opt to never put it back in.


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[tmontague]

I'm pretty sure the sedan and hatch are the same forward of the axle. I'll be sitting on the resonator for a bit until the exhaust tone settles in over the next couple months. After that I would sell it to you if the price if worth it (not sure what they go for).

I was going to hold onto it in case I ever needed to go back to stock or wanted to tone the noise down. That being said, I won't ever need to go back full stock as I don't think I'll ever sell my Yaris and so far I'm pleased with the sound.