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Straight Pipe 13" wrx??? No mufflers or resonator.

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Straight Pipe 13" wrx??? No mufflers or resonator.

Old 03-18-2013, 05:02 PM
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Straight Pipe 13" wrx??? No mufflers or resonator.

Having a straight pipe from the cats. No resonator or muffler.

Has anyone done this before or heard of this before?

Too loud? Sounds nasty? Good? Too much drone? Raspy? Whats your opinion?

If so post vids. I cant seem to find any online.
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Old 03-18-2013, 05:29 PM
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I didnt take video of mine, but I had a straightpipe turboback with only the high flow cat in my dp. It was loud as hell. It sounds good, but its too raspy and drones like crazy. I put a resonator in my midpipe and it sounds way better. Still very loud (louder than an n1) but I love it.

If you are still running the stock downpipe, it probably wont be crazy loud even if you don't have a resonator...

Where are you located?
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Old 03-18-2013, 05:32 PM
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Originally Posted by norcalbmxer4u View Post
I didnt take video of mine, but I had a straightpipe turboback with only the high flow cat in my dp. It was loud as hell. It sounds good, but its too raspy and drones like crazy. I put a resonator in my midpipe and it sounds way better. Still very loud (louder than an n1) but I love it.

If you are still running the stock downpipe, it probably wont be crazy loud even if you don't have a resonator...

Where are you located?
Yes i am running the stock downpipe. I was planning to just use straight pipe from the catback was afraid of it being to raspy. I like loud but not raspy.

I have an appointment this wednesday to get it done. I still have a choice to put just do an axle back delete. Or, (exhaust guy said) install a glass pack in replace of the resonator. Whats your opinion on that?

I am located in south san francisco.
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Old 03-18-2013, 05:34 PM
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If you wanna meet up tomorrow you can hear mycar and I can show you what your sound options are before you go to the muffler shop... ill pm you my number
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Old 03-18-2013, 05:35 PM
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Originally Posted by norcalbmxer4u View Post
If you wanna meet up tomorrow you can hear mycar and I can show you what your sound options are before you go to the muffler shop... ill pm you my number
What is your setup?
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Old 03-18-2013, 05:38 PM
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I had it done on my 08 wrx utilizing my TXS midpipe and catless DP the midpipe did have a resonator in it and it was very loud and deep. But really quiet at idle once it's warmed up. You do lose some power and response as you take away a lot of backpressure from the turbo. I noticed this difference once I put on my TXS mufflers on. It was fun for the few weeks and then it got old really fast.

Last edited by Imprezard; 03-18-2013 at 05:51 PM.
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Old 03-18-2013, 05:53 PM
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Originally Posted by Imprezard View Post
I had it done on my 08 wrx utilizing my TXS midpipe and catless DP the midpipe did have a resonator in it and it was very loud and deep. But really quiet at idle once it's warmed up. You do lose some power and response as you take away a lot of backpressure from the turbo. I noticed this difference once I put on my TXS mufflers on. It was fun for the few weeks and then it got old really fast.
Sounds like maybe i should just delete my mufflers until i can afford a 1000$ system?
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Old 03-18-2013, 06:45 PM
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Originally Posted by Imprezard View Post
I had it done on my 08 wrx utilizing my TXS midpipe and catless DP the midpipe did have a resonator in it and it was very loud and deep. But really quiet at idle once it's warmed up. You do lose some power and response as you take away a lot of backpressure from the turbo. I noticed this difference once I put on my TXS mufflers on. It was fun for the few weeks and then it got old really fast.
Backpressure is bad on a turbo car...
Here is a clip from a garrett turbo engineer:

***N/A cars: As most of you know, the design of turbo exhaust systems runs counter to exhaust design for n/a vehicles. N/A cars utilize exhaust velocity (not backpressure) in the collector to aid in scavenging other cylinders during the blowdown process. It just so happens that to get the appropriate velocity, you have to squeeze down the diameter of the discharge of the collector (aka the exhaust), which also induces backpressure. The backpressure is an undesirable byproduct of the desire to have a certain degree of exhaust velocity. Go too big, and you lose velocity and its associated beneficial scavenging effect. Too small and the backpressure skyrockets, more than offsetting any gain made by scavenging. There is a happy medium here.***

***For turbo cars, you throw all that out the window. You want the exhaust velocity to be high upstream of the turbine (i.e. in the header). You'll notice that primaries of turbo headers are smaller diameter than those of an n/a car of two-thirds the horsepower. The idea is to get the exhaust velocity up quickly, to get the turbo spooling as early as possible. Here, getting the boost up early is a much more effective way to torque than playing with tuned primary lengths and scavenging. The scavenging effects are small compared to what you'd get if you just got boost sooner instead. You have a turbo; you want boost. Just don't go so small on the header's primary diameter that you choke off the high end.***

***Downstream of the turbine (aka the turboback exhaust), you want the least backpressure possible. No ifs, ands, or buts. Stick a Hoover on the tailpipe if you can. The general rule of "larger is better" (to the point of diminishing returns) of turboback exhausts is valid. Here, the idea is to minimize the pressure downstream of the turbine in order to make the most effective use of the pressure that is being generated upstream of the turbine. Remember, a turbine operates via a pressure ratio. For a given turbine inlet pressure, you will get the highest pressure ratio across the turbine when you have the lowest possible discharge pressure. This means the turbine is able to do the most amount of work possible (i.e. drive the compressor and make boost) with the available inlet pressure.*
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Old 03-18-2013, 07:21 PM
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Originally Posted by norcalbmxer4u View Post

Backpressure is bad on a turbo car...
Here is a clip from a garrett turbo engineer:

***N/A cars: As most of you know, the design of turbo exhaust systems runs counter to exhaust design for n/a vehicles. N/A cars utilize exhaust velocity (not backpressure) in the collector to aid in scavenging other cylinders during the blowdown process. It just so happens that to get the appropriate velocity, you have to squeeze down the diameter of the discharge of the collector (aka the exhaust), which also induces backpressure. The backpressure is an undesirable byproduct of the desire to have a certain degree of exhaust velocity. Go too big, and you lose velocity and its associated beneficial scavenging effect. Too small and the backpressure skyrockets, more than offsetting any gain made by scavenging. There is a happy medium here.***

***For turbo cars, you throw all that out the window. You want the exhaust velocity to be high upstream of the turbine (i.e. in the header). You'll notice that primaries of turbo headers are smaller diameter than those of an n/a car of two-thirds the horsepower. The idea is to get the exhaust velocity up quickly, to get the turbo spooling as early as possible. Here, getting the boost up early is a much more effective way to torque than playing with tuned primary lengths and scavenging. The scavenging effects are small compared to what you'd get if you just got boost sooner instead. You have a turbo; you want boost. Just don't go so small on the header's primary diameter that you choke off the high end.***

***Downstream of the turbine (aka the turboback exhaust), you want the least backpressure possible. No ifs, ands, or buts. Stick a Hoover on the tailpipe if you can. The general rule of "larger is better" (to the point of diminishing returns) of turboback exhausts is valid. Here, the idea is to minimize the pressure downstream of the turbine in order to make the most effective use of the pressure that is being generated upstream of the turbine. Remember, a turbine operates via a pressure ratio. For a given turbine inlet pressure, you will get the highest pressure ratio across the turbine when you have the lowest possible discharge pressure. This means the turbine is able to do the most amount of work possible (i.e. drive the compressor and make boost) with the available inlet pressure.*
So basically your saying, it isnt good to run straight pipe from the cars due to our cars having the turbo?

With keeping the resonator on make a difference? Prob not? What would you recommend?
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Old 03-18-2013, 07:24 PM
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You may lose some low end going with a straight pipe. There won't be any peak power gain from it. Not to mention it will sound terrible. It's one of those thing that might be fun while you're installing an exhaust to drive it down the street and back, but in the longer run you will want better sound, less drone, and the ability to drive without ear plugs.
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Old 03-18-2013, 07:26 PM
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Why are almost all your threads posted in the Vendor, Tuning, Service, and Parts Review section?
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Old 03-18-2013, 07:55 PM
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Originally Posted by 13subaruwrx View Post
Having a straight pipe from the cats. No resonator or muffler.

Has anyone done this before or heard of this before?

Too loud? Sounds nasty? Good? Too much drone? Raspy? Whats your opinion?

If so post vids. I cant seem to find any online.
I had that exact setup. I'll post a video here soon
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Old 03-18-2013, 07:59 PM
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Old 03-18-2013, 08:01 PM
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Originally Posted by 13subaruwrx View Post
So basically your saying, it isnt good to run straight pipe from the cars due to our cars having the turbo?

With keeping the resonator on make a difference? Prob not? What would you recommend?
Its best to have a free flowing exhaust on a turbo car. Straight pipe would be bad if you didnt have a turbo. It will be fine on your car.

I pmed you my number. Shoot me a text if you wanna meet up to hear my straight pipe with a resonator...
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Old 03-18-2013, 11:43 PM
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Originally Posted by norcalbmxer4u View Post
Backpressure is bad on a turbo car...
Here is a clip from a garrett turbo engineer:

***N/A cars: As most of you know, the design of turbo exhaust systems runs counter to exhaust design for n/a vehicles. N/A cars utilize exhaust velocity (not backpressure) in the collector to aid in scavenging other cylinders during the blowdown process. It just so happens that to get the appropriate velocity, you have to squeeze down the diameter of the discharge of the collector (aka the exhaust), which also induces backpressure. The backpressure is an undesirable byproduct of the desire to have a certain degree of exhaust velocity. Go too big, and you lose velocity and its associated beneficial scavenging effect. Too small and the backpressure skyrockets, more than offsetting any gain made by scavenging. There is a happy medium here.***

***For turbo cars, you throw all that out the window. You want the exhaust velocity to be high upstream of the turbine (i.e. in the header). You'll notice that primaries of turbo headers are smaller diameter than those of an n/a car of two-thirds the horsepower. The idea is to get the exhaust velocity up quickly, to get the turbo spooling as early as possible. Here, getting the boost up early is a much more effective way to torque than playing with tuned primary lengths and scavenging. The scavenging effects are small compared to what you'd get if you just got boost sooner instead. You have a turbo; you want boost. Just don't go so small on the header's primary diameter that you choke off the high end.***

***Downstream of the turbine (aka the turboback exhaust), you want the least backpressure possible. No ifs, ands, or buts. Stick a Hoover on the tailpipe if you can. The general rule of "larger is better" (to the point of diminishing returns) of turboback exhausts is valid. Here, the idea is to minimize the pressure downstream of the turbine in order to make the most effective use of the pressure that is being generated upstream of the turbine. Remember, a turbine operates via a pressure ratio. For a given turbine inlet pressure, you will get the highest pressure ratio across the turbine when you have the lowest possible discharge pressure. This means the turbine is able to do the most amount of work possible (i.e. drive the compressor and make boost) with the available inlet pressure.*
I should have used a better word instead of backpressure because that's not the problem, exhaust gas velocity is what decreases with both too big and too small of piping which is why you see only 3" aftermarket setups with cats, resonators and mufflers which help keep the velocity at an efficient rate. You do need proper velocity to scavenge your cylinders, and the uppipe is designed to keep sufficient velocity levels so that you can successfully scavenge your cylinders and spool the turbo. Having a restricted (relative) exhaust post turbo means that the turbo has to work harder to create the same level of boost and the same effect applies for a more free exhaust. You are right you want as little back pressure after the turbo as possible.
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