I just installed an electric cutout on my Borla exhaust. I have it after the Y on the straight pipe in the recessed area under the rear passenger seat, just before it goes over the axle. I have BBK shorty headers with no cats. I love the Borla, but was looking for a couple extra HP, and I personally love a louder exhaust (if it sounds"good"). It sound INSANE with the cut out open. I am totally happy with the sound. The weird thing is it seems to have MORE power with the cut out closed and using the Borla. When I take off with the cutout open it "***** and gets" and sounds sick, but when I take off with the cut out closed it roasts the tires and I get a lot of wheel hop, so obviously there is some more torque at take off with it closed. To me that doesn't make any sense though. Could it be because of the back pressure? It seems that when I'm actually cruising that it is more responsive with the cutout open. Any opinions on this? Is it because the car is tuned for the Borla? Do I need to re-tune it for the cutout?

 

Theoretically, you should have a few more hp up top with the cutout open, and few hp less down low due to less back pressure. Most people do not need a retune

 

No you dont need a retune. Sometimes because of the loudness it seems that your car is slower but in reality it should be the other way around. Are you running a 3" Y-Pipe?

 

I have the same setup and had the cutout there as well. I ran the same times with it open and closed, but I swore I felt more low end with the cutout closed. I think this is typical.

 

I've found that cutout open changes how much timing
the motor can take, which (increasing cylinder charge)
is kinda the point. But I've also seen that the air mass
change only happens at higher RPM, not down low. So
my opinion is that effects on low-end torque are mostly
imaginary.

 

I thought my car slowed down when I went from a catted y to an off road y pipe. Everyone told be it just feels that way because its so much louder.

 

Why would you install a cutout on a system that already has a muffler bypass built into the catback?!

 

Thanks everyone for your replies. My mechanic agrees with HCI2000SS.He said the back pressure when it is closed is causing that little bit of extra torque. The car does NOT feel slower. I Just smoked 2 guys on rice rockets yesterday on the highway. They were messing around with some guy in a WRX Subaru. When I got up to them I was doing about 80 and they cracked it as soon as I got to them. I totally burned them and still had throttle to go (i was doing 145). It definitely has more throttle response when I'm already cruising. However from a dead stop if I have the cutout open it just catches and goes, whereas if I have it closed it absolutely ROASTS the tires and the wheel hop is ridiculous. Nothing imaginary. I took my mechanic for a spin today, we went from a dead stop to 60 with the cut out open and then again closed, two times each. Both times closed it spun 'em - with the tire hop. When starting from a dead stop open it squealed them for just a second and took off. We then tried it from 30mph and stomped on it, both open and closed. It was more responsive open. I've decided to just run it open. Out of all the mods and bolt-ons that I've done, I think the electric cut-out has been my favorite and has given me the most gains. I didn't think it would really make much of a difference other than the sound. Maybe the combination of the ram air/cold air intake/ and cat deletion along with the cut-out is just allowing the engine to really breathe and the cut-put was just the Icing on the cake. I don't know. The couple of seconds that it spins them while it's closed is made up for by it just taking off while it's open. I'm going to install some lower control arm relocation brackets to take care of the wheel hop when I am running it closed. Blackpanther99 asked what size the pipe was... it's all 3 inch right up to and going into the Borla muffler, then 2 1/2 (it may actually be 2.75) coming out. Thanks again all for your replies and opinions.

 

If your car is basically stock, you should make a little more torque with it closed and a little more HP open. the way I understand it is at low rpm the engine needs some back pressure to help making compression. At high rpm a open cut out should help with getting the exhaust out faster making a little more HP. to be honest I'm surprised that it make a difference at all. the Borla exhaust is basic a strait through design and you can tune the sound of it through the different size baffles. just my opinion.

 

I haven't been back to the track after I got my tune, but I got my E-cutout installed after I did LT, Catted Y, and motor mounts. I too had the same feeling. My "butt dyno" said that my car felt quicker with the cutout closed than open.
I went to the track and did about 10 passes with it open and closed half/half, and my times were definitely a little better with it closed.

I eventually got a tune, because emissions was coming up, and I had to tune out my O2 codes. They did a quick tune with the cutout open, but again, I haven't been to the track since, and also since then, my cutout motor broke...

 

I have dual electric cutouts after headers, car is cammed and a little under 400 rwhp. YES I lose a LOT of torque with cutouts open. A LOT. I couldn't believe the difference and in fact when I'm toying with another car on the road I'll open the cutouts to make some noise, but if we hit a red light I'm closing them QUICK!!! I want the torque from the line! I have the A4 and I can pull the switch opening cutouts while I'm running through 1st through 3rd so I get more horses at the end.

If I open them about a quarter or even half way open, I still have most of my torque. but full open I'm gassing it and it goes nowhere fast. I want to test at the track, since the lower torque and higher horses may play well into not spinning tires but will take some practice and testing.

Good run with the WRX, but Regarding launching with a WRX from a 'dead stop'....good luck. Even with cutouts closed it will be ugly.

 

They actually make a cutout for the borla that goes where you put the adjustable plate at. I was hoping this was what the OP had.

 

Read the first two sentences of this thread.

 

I did. That's why I made the comment I did.