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Old 11-15-2006, 06:18 PM   #1
D-Speed 2.5
Scooby Specialist
Member#: 29516
Join Date: Nov 2002
Chapter/Region: RMIC
Location: Denver
2005 WRX Wagon
Former GC O.G.

Default The Official Cutout Thread

After having my electric exhaust cutout for almost a year and a half, I figured I would start a thread that can help others in their decision to go with an exhaust cutout. Many other members on this site have cutouts and they should also share their experiences in this thread.


EDIT (6/1/08): DON'T BUY A BADLANZ CUTOUT! He has never been able to create a cutout that is on par with the other alternatives out there. If I were to do over again, I would spend a bit more for a QTP, DMH, or ATP.

While all cutouts leak, the Badlanz cutouts seeming leak worse/quicker than others.

(I know there are more but these are all I can think of for now)

There are many threads about the subject on nasioc. Some of which are listed below:

I think this thread has the most information:

Here are some others:


1. Cutouts are welded into the downpipe
2. Cutouts are insanely loud! Take the loudest Subaru exhaust you have heard and multiply it by 3. Cutouts make Harleys sound tame. It will make your ears ring.
3. Cutouts will spit flames out under the car
4. Cutouts are almost unbearable to use in stop and go traffic because of the fumes.
5. Cutouts will leave a lot of soot under and on the sides of your car.
6. Electric cutouts will all eventually leak from being over torqued over time. The leak sounds like a baseball card in bicycle spokes. If you already have a medium-loud catback, you won’t hear it. I have a STi axle back, thus I can hear my leak.
7. Electric cutouts MUST be sealed around the motor with silicon or something similar. My cutout failed to corrosion after only 6 months due to rust. Since sealing the motor assembly, I haven’t had a problem.
8. There is usually ground clearance issues associated with cutouts so make sure you have properly test fit where your cutout will sit once installed.


ERZ DP w/ BadLanzHPE cutout welded in:
-$150 for BadlanzHPE cutout
-$100 for welding and installation (included wiring)

A pic to show how much fuel collects in the cutout (hence flames, I was running rich):

Also, in the top left corner of that pic, you can see how the motor rusted out because I didn't seal the rubber boot that protects the motor with silicon. You must make sure this part of your cutout gets sealed with silicon or something similar!


UNTUNED: My performance observations were (stock turbo):
-Boost came on about 200 rpm sooner
-Power felt much more linear with it open (smoother power delivery)
-Gained about .5-1psi of boost (depending on gear)
-The car felt much stronger at the top of the rev range (boost seemed to hold on longer)
-Never saw a single CEL

Untuned, the car was easily faster than stock STis and stage 2 WRXs. I felt that much of my power was coming from my cutout. While I was happy with my car, I wanted more power thus I finally went in for an EcuTEK tune from Harvey at Super Rupair in Boulder, CO.

TUNED: (much of this is what the tuner said)
-“Wow this car spools quickly with that thing open”
-“This car reacts really well to changes in boost”
-“Power holds really well until redline”
-“It seems as if the whole curve has moved to the left”

TUNING NOTES: I went for 20k miles on my cutout untuned, stock turbo, stock ECU. I was running rich as hell, 10.0:1. Closed it would creep up to 10.5:1. When I came in for my tune (EcuTEK), my tuner was pretty surprised by this. For my baseline run, cutout open, I put down 200whp (6,000ft above sea level)which is what most stock turbo guys leave at fully tuned from the same dyno. After a couple of hours, I left at 227whp and 225wtq. My car did not respond positively from changes in timing since I think the ECU was so used to the cutout already. Instead, the car made big power from additional boost and leaning out the AFRs to 11.0:1.

HOWEVER, ALL CARS RESPOND DIFFERENTLY! Just because I was running fine for 20k, doesn’t mean that the next guy will. It was really odd that my car was running rich on the stock ECU but I think that may be a rarity.

My dyno charts (sorry, I don’t have an open vs. closed comparison):

Stock STis put down 215whp on this dyno:

A friends dyno chart (different dyno) that shows a comparison between open and closed on his ’04 WRX:

Keep in mind that this is uncorrected, 100+ degrees in the dyno room, and at about 5,500 ft in elevation. Its hard to see but peak change in power was 17whp and peak change in torque was 25wtq. These were back to back runs with no additional tuning.


Cutouts are not for everyone. Most do not like the noise, I however do. I also really enjoy the added power. However, I mostly enjoy the ability to go from super loud, to super quiet at the flip of a switch. This is really nice for those who have girlfriends or wives who hate the noise that an aftermarket exhaust brings.

I hope others will contribute their experiences as well so that all questions can be easily answered in the future.

Thanks for reading,

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Last edited by D-Speed 2.5; 06-01-2008 at 11:58 PM.
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