More Mk7 Turbo Muffler Delete Flow Testing


In a discussion of upgrade parts the subject of the Mk7 turbo muffler delete (TMD) came up. I offered that the part wouldn’t provide a performance gain, somebody else offered a snippet from the Racingline product description listing numerous benefits the TMD provides. I restated that they do not provide a gain and the other person offered the following, paraphrased for brevity:

I posted the Racingline info cause they area well established orginization that works closely with factory VW to produce after market parts. They also actually test their parts…. Cant image a company like Racingline staying in business long if what their selling doesnt work….

I understand where that person is coming from, I’d like to believe products do what they are claimed to, so I contacted Racingline to get some information. More on that effort in another post, but that discussion along with the delivery of the final parts for the aFe Power BladeRunner charge pipe kit, which included a turbo muffler delete, led me to think about yet another round of turbo muffler delete testing.

Mk7 GTI Turbo Muffler Delete
aFE (Top Left), Generic aftermarket (Top Right), Stock (Bottom Center)

Test Procedure:

I’ve beaten this product thoroughly in previous test efforts, so I was thinking of something different that I could do. Short of installing it on my GTI, which would be more effort than I wanted to undertake, I decided I could try installing the TMD onto a turbocharger and flow test through the turbo compressor housing and out the TMD.

The aFe Kit had originally been sent with a hose that connects to the stock TM. I had ordered a kit that came with an aFe TMD and larger hose, but there was a couple of month wait to get the final parts. With both hoses now available I had a good setup to test the stock TM and aftermarket turbo muffler delete.

aFe BladeRunner Stock GTI and aFe fit couplers

Prior to testing the TMDs the flow bench undergoes a calibration check to make sure it is setup properly to give accurate measurements.

400 CFM Calibration Plate

For the parts test an adapter is selected that fits the outlet of the silicone hose and joins the hose to the flowbench. The other end of the hose will attach to the Turbo Muffler/Delete. The TM(D) is installed in an IS20 turbocharger. The compressor housing is open to the atmosphere as well as the diverter valve (DV) port. The DV port is open so that air can also be drawn in through it.

aFe BladeRunner Turbo Muffler Delete on IS20 Turbocharger
aFe BladeRunner Turbo Muffler Delete on IS20 Turbocharger

Once the turbo muffler is attached to the silicone hose the flowbench is operated at a test depression of 28″ of H2O and the airflow through the system is recorded.

The compressor wheel is stationary during the test. Prior testing of turbine housing flow has shown that allowing the wheel to spin reduces the airflow.

The test is then repeated with the other TM(D)s.

Test Results:

The aFe Power BladeRunner turbo muffler delete flowed 140 CFM @ 28″ of H2O.

The second TMD tested is a generic product that has a flared opening and fits with the stock size silicone coupler.

Generic Turbo Muffler Delete flow test with IS30 turbocharger
Generic Aftermarket TMD

This turbo muffler delete flowed 139 CFM @ 28″ of H2O.

The final product is the GTI stock Turbo Muffler.

GTI Stock Turbo Muffler Flow Test
TI Stock Turbo Muffler Flow Test

The stock Turbo Muffler flowed 138 CFM @ 28″ of H2O.

The test results are combined in the following chart:

Note: The margin of error of the flow test is approximately +/- 2 CFM.


A flow test was performed to evaluate airflow through three turbo muffler devices installed on an IS20 turbocharger. The airflow measured through each product ranged from a high reading of 140 CFM to a low reading of 138 CFM at 28″ of H2O. This 2 CFM range is equivalent to the margin of error of the test apparatus. There is no significant difference in the products tested following the test method described above.

6 thoughts on “More Mk7 Turbo Muffler Delete Flow Testing”

  1. Thanks for confirming. Id be interested in seeing if there is more compressor surge with the TMD vs the stock one.

  2. Hey what do you think would happen if you were to cut everything off the turbo muffler up to the flange so it was just an open area behind the flange.

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