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BooSTIng
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Discussion Starter · #1 · (Edited)
Hello all, with tax time/racecar fund, right around the corner I'm starting to really think hard about the path I want to take with my STi. Initially I was pretty set on the grimmspeed catted downpipe. However, I do plan on going with an external wastegate. So, thinking to myself, knowing that the STi is less prone to boost creep than its counterpart, should I just start off catless? I mean The few hundred bucks I would save with a catless DP when compared to a catted would almost pay for the wastegate itself. (looking at the tial MV-S 38mm wg) Then all I would need is the uppipe and tune.

Intially these were my plans for this year:

-GS catted dp
-Invidia q300
-GS intake
-GS ebcs
-accessport
-protune

Now I am leaning more towards this set up:

-bellmouth catless downpipe
-invidia q300
-GS uppipe for ewg
-tial 38mm wg
-GS intake
-GS ebcs
-accessport
-protune

Here is my dilemma. The few sites that I regularly shop from have very limited options for a bellmouth/catless DP. I am leaning towards the CNT one. But have read MANY terrible reviews, and a handful of good ones. I understand that a downpipe is a downpipe, but I prefer and would rather pay a few extra bucks for good craftsmanship and fitment.

So, with that said, what are your personal thoughts on the CNT dp, and what other bellmouth and catless downpipes are on that market that are better, or equal to brands such as invidia and GS. Links and thoughts are much appreciated.
 

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I hate my catless downpipe. Less because of boost creep issues and more because it will make your eyes water driving it

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BooSTIng
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Discussion Starter · #4 ·
I hate my catless downpipe. Less because of boost creep issues and more because it will make your eyes water driving it

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Yeah the smell is something I would like to avoid. But with talking to several people they seem to think that catless is the way to go when running an ewg setup with a dump tube.
 

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BooSTIng
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Discussion Starter · #5 ·
I prefer catted. I mean where I live I have zero emissions testing I have to worry about. So that isn't the issue. I guess I could still go with a bellmouth catted downpipe, because having the divorced wastegate is pointless when running external. I'm just trying to save money where it can be saved.

What is a good brand that has a bellmouth CATTED downpipe? Seems all the newer downpipes have divorced wastegate tubes. (i.e. invidia, GS)
 

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BooSTIng
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Discussion Starter · #6 ·

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So, with that said, what are your personal thoughts on the CNT dp, and what other bellmouth and catless downpipes are on that market that are better, or equal to brands such as invidia and GS. Links and thoughts are much appreciated.

CNT is a cheapo knockoff brand. A pipe is a pipe, and they work out for some people, and the also crack and leak for other people.. I would imagine rust is also a concern if you live where it snows, since the metal used is subpar. Some people also have issues getting it to fit.

I've had a TurboXS catless downpipe since 2003 and it has served me well.



Yeah the smell is something I would like to avoid. But with talking to several people they seem to think that catless is the way to go when running an ewg setup with a dump tube.

Ehh.. having an EWG you will see even less gains going catless than you would running the stock IWG. Since exhaust gasses are able to bypass the stream before they even reach the turbo there is less exhaust passing through the rest of the exhaust, therefore the catalytic converter poses less of a restriction. I suppose it is the way to go if you're trying to save money, since catalytic converters are relatively expensive on their own.
 

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BooSTIng
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Discussion Starter · #8 ·
Thanks for the reply. I have never had such a hard time deciding on a downpipe. But the Xforce one is interesting. It is a bellmouth, plus I can run catted or catless. Just never heard of them before. Also, the cat is very far back on the exhaust stream. So I would I still get the same benefits of a regular catted downpipe where the cat is located closer to the turbo?
 

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Master Baiter
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I've never had a smell issue with catless vehicles when driving them. It's just sitting behind them that always bothered me. Personally, I'd try save money and go catless, since creep won't be an issue, and the illegality is the same.

WRX-maniac said:
Thanks for the reply. I have never had such a hard time deciding on a downpipe. But the Xforce one is interesting. It is a bellmouth, plus I can run catted or catless. Just never heard of them before. Also, the cat is very far back on the exhaust stream. So I would I still get the same benefits of a regular catted downpipe where the cat is located closer to the turbo?
All things equal, the farther down the exhaust path the catalyst is located, the less restriction it will introduce, at the expense of higher emissions.
 

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Does anyone know anything about Xforce downpipes??? Found this on RSD. I am NOT a fan of DP's that are 2 piece because they are more prone to leaks. But the fact that it comes with a cat or catless section is interesting. Thoughts?

https://www.rallysportdirect.com/fi...-sw08-kitb-x-force-pro-series-catted-downpipe
Man you are speaking my downpipe today. This is my experience with my DC sports. It's not complete bottom shelf garbage, but it's far from best of the heap.

The catless part I mentioned is a no brainier. My real problem is what you mentioned with the gasket sealing. I've replaced exhaust gaskets in it at the point it mates to my cat back a couple times, and the break before the second pipe twice. I've noticed the gasket issues get worse when I drive harder, perhaps heat warp, I don't know.

As far as rust, mine still looks pretty good and it's been in the car since the previous owner bought it in 2010

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BooSTIng
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Discussion Starter · #11 ·
I've never had a smell issue with catless vehicles when driving them. It's just sitting behind them that always bothered me. Personally, I'd try save money and go catless, since creep won't be an issue, and the illegality is the same.



All things equal, the farther down the exhaust path the catalyst is located, the less restriction it will introduce, at the expense of higher emissions.
What downpipe would you recommend Matty? I want a bellmouth since I will be going ewg. Catted or catless doesn't really matter to me. But I want a company I can depend on for fitment, welds, and material used. I know many people say that it is just a pipe. But I am a firm believer in that you get what you pay for. I don't mind paying more if the pipe meets my standards. I have always had invidia dp's and have always been more than happy. Problem is that I cant find, or maybe they stopped making the bellmouth.
 

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BooSTIng
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Discussion Starter · #12 ·
Man you are speaking my downpipe today. This is my experience with my DC sports. It's not complete bottom shelf garbage, but it's far from best of the heap.

The catless part I mentioned is a no brainier. My real problem is what you mentioned with the gasket sealing. I've replaced exhaust gaskets in it at the point it mates to my cat back a couple times, and the break before the second pipe twice. I've noticed the gasket issues get worse when I drive harder, perhaps heat warp, I don't know.

As far as rust, mine still looks pretty good and it's been in the car since the previous owner bought it in 2010

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You are one of the reasons why I want to avoid a 2 piece downpipe lol. Reading your horror stories about exhaust leaks and stuff makes me want to avoid it entirely if possible.
 

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A co-worker who builds DSM said if you can find one with vband clamps it solves the issues, so that might be an idea if it can move the cat further away from the turbo.

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BooSTIng
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Discussion Starter · #14 ·
I'm kind of leaning towards that Xforce one. Its cheaper than most and I can change it from catted to catless. If the leaking ever gets bad like yours, ill just take it somewhere and have it welded.

Unless someone can give me a better alternative.
 

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I personally like HKS and have never had problems. I'm running a catless bellmouth HKS DP.....my whole exhaust is HKS actually lol but I plan on getting a GS UP with a tial ewg this tax season like you're doing
 

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My TurboXS downpipe is a two piece, and the gasket between the two halves has never leaked in 13 years of owning it.. in spite of the fact that I've removed and reinstalled it at least a dozen times on two different cars, and never replaced the original gasket.

My ETS downpipe is also two piece, but it uses a v-band connection.
 

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My TurboXS downpipe is a two piece, and the gasket between the two halves has never leaked in 13 years of owning it.. in spite of the fact that I've removed and reinstalled it at least a dozen times on two different cars, and never replaced the original gasket.

My ETS downpipe is also two piece, but it uses a v-band connection.
Since this is a downpipe thread, to solve my problem the leak Would it be more ideal to weld it or maybe have vbands put in?

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Since this is a downpipe thread, to solve my problem the. Would it be more ideal to weld it or maybe have vbands put in?

I like v-band connections for all exhaust components personally. They seal well, and have the ability to rotate to get things to line up just right. The downside though is that after being heat cycled several times it's not unusual to need to replace the clamp if you have to remove it for whatever reason.. and the clamps aren't exactly cheap compared to a normal gasket.
 

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WRX-maniac said:
What downpipe would you recommend Matty? I want a bellmouth since I will be going ewg. Catted or catless doesn't really matter to me. But I want a company I can depend on for fitment, welds, and material used. I know many people say that it is just a pipe. But I am a firm believer in that you get what you pay for. I don't mind paying more if the pipe meets my standards. I have always had invidia dp's and have always been more than happy. Problem is that I cant find, or maybe they stopped making the bellmouth.
If you're going with an EWG, there is ZERO benefit to going with a divorced / divided wastegate design (I have said this to you on multiple occasions). On a stock turbo, it's not going to really make a bit of difference, but if you decide to upgrade to something like a Blouch 1.5XTR, not having a bellmouth may hold you back a bit, but it might not (I haven't tuned enough cars with that setup difference to say). If you're deadset on Invidia, and want the bellmouth design, you can always get their divided downpipe and have the plate taken out for probably $20-50 or so in labor costs.

Invidia, as far as I know, has discontinued their bellmouth design; another option they have to cover for limited/minimal sales gains.

I haven't had the bad experience with the knockoff pipes in terms of them breaking down. The welds often look like they were done by Michael J Fox, but they've never broken apart and caused leaks (and I see much more snow / halite than you do down in MD). Fitment issues can usually be resolved by enlarging bolt holes with a drill, so it's never been an issue with me. Plus, if you buy from a reputable seller, and you tell them there's a fitment issue, they'll replace the part. If you're using the vehicle as your only means of transportation, that's not always acceptable, but that's where you need to choose between paying a premium is worth it or if you're willing to gamble on saving a few dollars. That said, a post-turbo exhaust leak is nowhere near the issue that a pre-turbo one is.

If you are really worried about quality, buy used. As much as I'd love to sell you a part from my vendor account, there are people looking to recoup what they can when they part a vehicle out, and you can save some money there. This isn't a wear item (the exhaust should last the life of the vehicle and then some), so strongly consider the used market, if what you want is available.
 

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Is there any reason specifically you don't want to go catted and want the EWG setup and catless? Unless you're going with a big turbo setup or something, you're essentially just making a strong smelling, melted bumper noise maker with the setup you're now wanting, haha.

I'm a huge fan of my GS Catted DP.
 
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