Race/Test pipe vs. Hollowed out OEM Mid-pipe

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Hapa88

Member

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2008 CB Mazdaspeed3

• Feb 5, 2009

• #1

So I was wondering how a hollowed out (de-Catted) OEM Mid-pipe would fair against a race/test pipe like the ********** or Corksport unit?

I mean if I can get most of the performance, still look stock, and get someone's used mid-pipe cheap, wouldn't that be ideal? What do you guys think?

 

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CnoTataymo

:

13 MX-5

• Feb 5, 2009

• #2

You'll gain about the same. The biggest restriction is the cat with the downpipe. If you can get a full downpipe all the way to the catback, that will net the most gains unless you go full turboback.

Stock cats are worth a lot. You're better off having an exhaust make you a testpipe.

 

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Cue

Member

:

Mazda CX-7 2008

• Feb 5, 2009

• #3

Test pipe upgrades give you a 3" pipe vs. the stock 2 3/4"

 

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Hapa88

Member

:

2008 CB Mazdaspeed3

• Feb 9, 2009

• #4

Cue said:

Test pipe upgrades give you a 3" pipe vs. the stock 2 3/4"

Click to expand...

So what does that gain if the rest of the stock piping remains unchanged at 2.75"?

 

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GoFast

Member

Contributor

:

2010 Flyin' Carpet

• Feb 9, 2009

• #5

Hapa88 said:

So what does that gain if the rest of the stock piping remains unchanged at 2.75"?

Click to expand...

a lot is to be gained. understand that mazda did a really great job with the catback part of this exhaust. there is very little to be gained, other than sound, if you go after market cb. the down pipe is definitely the restriction in this system.

 

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hectik1

Member

Contributor

• Feb 9, 2009

• #6

Definitely feel more in the midrange with the hollowed out cat. Sound improves a little also.

 

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Bonafide_Spd3

Member

:

2007 Mazdaspeed3 GT Cosmic Blue

• Feb 9, 2009

• #7

I read today in an import mag. that a test pipe on some lexus car gave it like 5 hp. and deleting a cat basically did nothing, all it did is make you lose gas mileage. You lose gas mileage with a test pipe as well. Just thought I would say something

 

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hectik1

Member

Contributor

• Feb 9, 2009

• #8

Bonafide_Spd3 said:

I read today in an import mag. that a test pipe on some lexus car gave it like 5 hp. and deleting a cat basically did nothing, all it did is make you lose gas mileage. You lose gas mileage with a test pipe as well. Just thought I would say something

Click to expand...

You don't mod for gas mileage!(inout)

 

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GoFast

Member

Contributor

:

2010 Flyin' Carpet

• Feb 9, 2009

• #9

Bonafide_Spd3 said:

I read today in an import mag. that a test pipe on some lexus car gave it like 5 hp. and deleting a cat basically did nothing, all it did is make you lose gas mileage. You lose gas mileage with a test pipe as well. Just thought I would say something

Click to expand...

i wonder how much of that is because you are getting on it a bit more because of the extra kick you get or sound?

 

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PCspeed3

Member

:

Pearl White Speed 3

• Feb 9, 2009

• #10

This test was done in the latest import tuner, you loose power with hollowed cat because of turbulence. Gain power with a same diameter test pipe.

 

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aaronc7

Banned

:

2007 Mazdaspeed 3

• Feb 9, 2009

• #11

likely the test was also done with a NA car, not turbo.

less backpressure is always better for turbo cars

 

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PCspeed3

Member

:

Pearl White Speed 3

• Feb 9, 2009

• #12

aaronc7 said:

likely the test was also done with a NA car, not turbo. less backpressure is always better for turbo cars

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THis is true, I should have said that. The test was done on a miata.

104 hp w/stock cat, 103 hp w/gutted, 105 hp w/test pipe...

 

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bykeryder4life

Member

• Feb 10, 2009

• #13

wow sounds like some pretty damn consistent #'s 103, 104, 105.........

 

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MSMS3

Member

• Feb 11, 2009

• #14

Bonafide_Spd3 said:

I read today in an import mag. that a test pipe on some lexus car gave it like 5 hp. and deleting a cat basically did nothing, all it did is make you lose gas mileage. You lose gas mileage with a test pipe as well. Just thought I would say something

Click to expand...

I don't know anything about what some NA Lexus will do with no cat or a gutted cat.

What I can say is that I have a 3" DP/RP combo into the stock cat back exhaust. I dropped a full second in 60-100 mph times. I just returned from a 324 mile trip on a single tank of gas, using 12.7 gallons. I ran 77-80 mph, sometimes a bit faster. That average is 25.5 mpg. The car now has about 8,000 miles and is probably fully broken in. Highway mileage has been gradually improving, but I think this is what to expect now in the long run. Around town and mixed city-highway driving averages around 20 mpg.

I have some difficulty concluding that deleting cats decreases mileage in our cars. While I can't say my mods increased fuel economy (that's not why I did them anyway), I can't find any reason to believe that they hurt fuel economy. The sole exception would be at WOT where the mods are producing more hp and torque. Obviously it takes more fuel to produce more power.

 

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Bonafide_Spd3

Member

:

2007 Mazdaspeed3 GT Cosmic Blue

• Feb 11, 2009

• #15

pcspeed that's what the car was. Good stuff, and that was the mag I was looking at. Thanks for clearing that up. But I have gotten worse gas mileage with my test pipe. I use to get 30 mpg on highway at 75 mph. And now I get 26-27 mpg