I did a little searching and found this post. I don't care about the pollution aspect as I'm running a straight through 3" turbo back, but the 500 hp comment was interesting. I'm going to do some more searching and see if there are any dynos.

"I dont like cut outs

A few reasons why

#1 - they fumigate you with poisionous exhuast fumes - nothing like a full exhuast without leaks to make your vehicle safe

#2 - Based upon my careful testing up to 500 whp there is virtually NO difference in power between a well designed 3" exhuast turbo back system (e.g. Buschur) and a fully open exhuast system - - opening a valve usually just makes more noise

#3 - Usually the effect of the cut out on a stock exhuast (which is what the cut out guys seem to want to use) and an open pipe is significant and results in being impossible to tune properly for both the cut out open and closed - meaning you would really need two maps. Of course if you were using a good exhuast the effect of the cut out would be less severe (almost nithing) and you prob would not need a seperate tune

#4 - If the cut out is in the wrong location (too close to engine) it can trigger false knock due to excessive noise and effect the MAF sesnor

# 5 - You must place your 02 sensor upstream of the cut out or you wont get an accuarte reading

In short - cut outs are a crude and ill advised solution on street cars and really dont offer any performance benefits over a properly designed 3" exhuast system. The principle benefit they offer is to make a lot of noise.


__________________
Experienced, Safe and Reliable tuner of all Evo and Subaru Ecus

Cobb Access Port Pro Tuner, Ecutek Dealer, AEM Certified, Aquamist Dealer, Dealer and Installs for Buschur Racing "

 

As with everything in life, you will find advocates and adversaries. Here are my comments to the adversary's responses:

1. Unless you are running a CAT, you are not doing the environment ANY good. Are you looking for performance gains or are you trying to be Mother Nature? You won't have the best of both worlds, regardless of this cut-out.
2. False. As I stated previously, I know first-hand that other people have made very nice gains with this setup. I am in the process of finding their before/after dyno sheets to prove this point.
3. The cut-out is positioned after the exhaust manifold, and will have no ill effects on the tuning. The tune is pretty much "dead-on" after the exhaust manifold.
4. Sure...any data to back-up this claim?
5. See #4.

Take this mod for what you want. Simply stated it is tried and proven.

 

Cool - I was just checking the positive and negative.

 

Why do you seem so set on trying to convince people that this works? You keep saying yeah it works its been proven but we havent seen anything besides your word. Most people want to know how it works and why its better than choice A or B before they shell out the money for it. If it works so good and you want people to believe you then buy it yourself and prove to everyone that this works. Im not saying it doesnt but you just have to understand the idea.

 

I have nothing "vested" in this product. I simply know that is WORKS. How, like I said in my initial post I have several friends with this mod and it NO SHIT works. I will post some links to their dyno graphs, but I am sure they will be questioned. The creator of this cut-out also provided some data as to the gains achieved on other cars.

Again, I get nothing out of the sale of this item. I have sat in other cars with this mod, and the butt dyno tells you it works when activated. My wife and I have too much other things going on right now and simply don't have the money (albeit how cheap it is) to do this mod on her Evo. Within the next month or two we will do it and will have solid data which substantiate the gains.

 

what if you ran this on the stock exhaust but mocked up a straight pipe that leads off of it to the back of the car...? that way the exhaust gas isnt expelled right under the car.

it would be like having the option to run a straight pipe or the stock exhaust at the flip of a switch.

 

A very nice option which avoids the all-but-restrictive factory CAT and the rest of the exhaust system!

 

my friend has the 4 inch cutout on his supra. Its awesome and he did make a lot more power but lost some torque. Anyways, the concept is great but he is experiencing exhaust leak now with it. He has sent it back 2 times now. Wish it didn't leak but he does make a little over 1k whp.

 

That is great...sort of! So far my friends haven't had any exhaust leaks problems, and all of them gained horsepower and torque from this mod!

 

I almost bought one of these for my DSM. It is great cause you can run a low boost setting with a stock looking exhaust and then when you want to run high boost setting if you have a dual boost controller or something can open the cut out and you instantly have a a big 3.5" straight exhaust. Would be very helpful to not get as many exhaust tickets if that has been a problem. I know on my eclipse I got a few so this would have helped, unless of course they looked under the car and saw it and then you would be in more trouble than just a loud exhaust.