From what I’ve read and experienced:
The gains on a stock exhaust cutouts are about the same as putting on a good aftermarket catback.
If you have already bought a performance catback, you’ll most likely see little to no gain overall.
But if you want more exhaust flow you’ll need to sweat a little for a Homemade exhaust cutout…
…which is not as easy as it seems.
But it is not science, I promise you will do it.
When mentioning exhaust flow, the noise it emits or even the power we are talking about are closely linked to each other.
It’s not possible to have one without the other.
But I strongly believe you don’t mind the noise, as long as there is more flow.
It’s a fact that an exhaust that’s straight through will also be highest flowing.
So that’s why I thought about sharing this DIY exhaust cutout for Dodge Challenger owners, that me and my friend Dave made on his 2010 Challenger R/T..
So first things first. If you want to make a homemade exhaust cutout, these are the raw materials you will need:
- The cutout assemblies (Example: QTP QTEC66K1 Dual Oval Low Profile Electric Exhaust Cutouts With Stainless Tips)
- The turndowns (Example: QTP Oval Turn Down)
- Switch (Example: Waterproof Illuminated Double Pole, Double Throw 3 Position Momentary On-Off-Momentary On Rocker Switch)
- Wire strippers and cutters
- Splices and shrink wrap
- Drill with small and large bits
- Aluminum ‘Speed’ tape
- Ty wraps
- Screw drivers
- Welder (or a welding capable shop)
First thing you need to do is some prep work on the switch assembly…
You’ll need to have a schematic ready to have a visual of what the stock switch assembly looks like:
Replacing The Switch
Note: As I said, this is an optional but recommended step.
If you are persistent enough to replace the switch by yourself, the following steps will help you do just that.
This is how the original switch looks like:
The things with this switch that I didn’t like were
1.) The looks. Rocker switch is the real deal.
2.) It was quite stiff, so much that it was quite possible the plastic molding to end up cracking over time with activation of the switch.
Here’s a side by side of the original switch, and the new one:
The wire terminals will transfer from one switch to the other without any terminal end replacements.
Step 1. Just transfer them from one switch to the other, but remember to keep the same order, you don’t want to mix up.
The QTP switch will use 2, 3, and 4.
The lamps are 1 and 5. Here is pic of the schematic on the QTP switch:
For this kind of switch it’ll be better off if you make the red lamp the momentary switch to open the cutouts and with that the amber to close them.
If you have the same switch from Quick Time Performance:
On the side of the lever you’ll see single wire jumpers to the other side of the switch.
Step 3.The next thing you need to do is put the jumpers on the side of the switch that you want to open the valve.
Referring to the 2nd schematic, the red lamp is 5A & 5B…
…you’ll want the single wire jumper on 4A & 4B.
Note: If this seems hard, don’t worry. If you experience failure or just mix up the wires or don’t come like the switch you can always wire it like the first schematic and it will most surely work.
Step 4. The next thing you’ll want to do is to wire up the lamps.
This will be a neat trick if you want the lamps to be lit anytime the valves could be moved.
To make this happen you need to splice in two runs of wire on the power wire (red) and two on the ground (black).
Step 5. Run the power to 1A and 5A and the ground wires to 1B and 5B.
There are two options you can do at this moment:
You can find a wire terminal to fit the switch…
…or you can just do it your self and solder them on.
I chose to solder.
If by any chance you have a power supply laying around then it’s good to be able to run a check up on everything.
When all of the wiring is done, it is best for you to wrap it in electrical tape to keep everything covered and secure.
Next up is the work on the car
Tip: Reassembling everything as it was can be tricky. If you are not advanced, I suggest you to take pictures on every step as a reminder of all parts’ location.
In the next few steps you’ll see how to put the switch in the knee panel.
Step 1. First, you’ll have to remove few snap panels.
As you can see from the pic, you need to pull on the vertical strip, and when it’s out you’ll see two clips, one on top and one on the bottom.
There is one hidden screw there for the knee panel:
Step 2. Pull the bottom door trim straight up too. There is another hidden screw, now for the corner trim.
You can see one more screw on the underside of the knee panel. It is in plain sight if you look up at it.
Step 3. By now the bottom part of the knee panel is pretty loose, you just need to give it a push downwards and back to pop out the clips holding the top.
Detach the connector for the trunk lever so you can get the panel out of the way.
Next you need a power source:
The power wires you want to use are the ones located in the center console power source. This is the case because it is only receiving power when the key is turned and it has sufficient amperage to operate the motors without concern.
Step 4. Pop off the center console molding:
Honestly, this panel is a bit of a Challenge.
It is only held in by the standard quick clips that are a real pain in the butt.
But still you’ll only need two flat blade screwdrivers to do it.
Go for the smaller bundle of wires. That’s what you’ll need
Step 5. It’s pretty clever to disconnect the battery .. just in case.
Step 6. Cut this wire bundle in a spot that will allow you a little room to work on both ends.
Step 7. Next you need to trim the covering back with a razor and strip the wire insulation back for a butt splice.
Step 8. Splice red and red back together on one side of the splice and black and black on another. A wire going to your switch is actually the other side of the slide :
Step 9. Next you’ll need to direct some wiring from the power wires you just tapped into to the switch location.
They are located below and to the left of the steering column.
There you’ll find a passage you can push the wire through from the center console to the left side of the knee panel without a hustle.
Step 10. You’ve come to a point where you need to cut a hole for the switch.
The best way to do this is with a drill that has a small drill bit.
A dremel would be good too.
This is easy one, just be patient and cut a straight hole enough for the switch to fit.
Something like this:
Step 11. Splice in both ends of your wire you ran from the center console to the switch.
Double check that the power wire (red) from the power source is going to the power wire on the switch with the fuse.
The most convenient for running the intermediate harness is to exit under the driver’s seat because there’s a unused drain plug there.
It is very easy to get there, too.
Step 12. Run the intermediate harnesses over to the right side of the knee panel and route them under the panel running back along the lower center console area.
It’s snug enough, so just push the both wires up in there and they won’t fall out.
Step 13. Run them all the way back to the middle of the driver’s seat then have them exit and go down under the driver’s forward/aft slider track:
Now it’s time to reassemble all the panels you’ve taken apart.
Wait, you still got work on the outside.
But before I go to that:
Under the driver’s seat you’ll see a black ‘drain’ plug of some sorts that will come in handy because luckily for us this is an unused port.
You can see it here, but it was covered with some sort of tape:
The Work on the Outside
Your DIY Exhaust Cutout is not done yet.
Under the driver’s seat there is a small piece of carpet that is cut. You’ll see the Power Seat wires going through it.
If you look in that hole you’ll notice a round bump in the under flooring that is right above that drain plug.
Step 1. Even though it sound like a lot of work the only thing you are going to do is take a big drill bit and drill through part of that drain plug and through the under flooring to allow a hole big enough for your intermediate harness to go though.
You won’t want to drill a huge hole for the connectors, because it might just leave you with some loose ends. Instead you can drill a hole that will be big enough just for the two wire harnesses to go through and cut the intermediate harness.
Inside the harness the wires are black and red as well, so just splice them back together the way they were.
It’s certainly better to keep the splices on the inside of the car.
Note: One thing you want to notice is that the under flooring is not a metal. It’s some sort of soft formed putty. Why I am pointing this out is to not press hard with your drill and expect for some sort of a metal to resist the drilling.
Just put light pressure and the drill will easily go through it.
Step 2. Feed your wires through:
I worked on the right cutout first, and I believe you’ll probably want the same.
The cutout location is where the exhaust comes down from the cat converters…
…and right after where it turns inboard is a nice location.
In the next picture you will see the right exhaust cutout and the intermediate harness.
Step 3. Direct the harness under the aluminum shielding and over to this inner support block, or whatever the technical term is for that thing.
Step 4. At this point you need to continue routing the harness left and under another aluminum shielding. Right about here is where you’ll see the left cutout harness.
Also note that this is a god pic of one of unused drain plugs I mentioned. Even though this plug is forward of the one you want to enter:
Step 5. Here is the left cutout and where you can securely mount it:
Step 6. Run both wires under some aluminum speed tape back to the exit hole:
Step 7. Coil up all your excess wire harness and stow them under the driver’s seat neatly. Make sure they are secured to the seat adjustment motor too so they move with the seat and don’t get pinched.
You are ready to go.
Here is a pic of the installed switched with power:
Here are the two valves:
Note: Friendly folks at a local monro did the labeling because I didn’t have the necessary tooling to do that.
That’s why the labeling is level: for dummies. :)
I only filed the right down turn just a little on the one corner because it was a little close to the valve.
It cleared but I just needed to make sure that with a little wear it still would:
At this point if you did not welded the cutouts on, you still need to protect them from moisture and other influences.
Do this by putting a bag over the connectors under the car and wrap it up tight and firm.
If you are in to welding and know a lot about cars, you probably know and want to do it by yourself.
We on the other hand recommend that you get an appointment at your local welding-capable shop.
Here is video we could only take by phone, so just listening to this won’t tell much difference.
1st rev is with stock exhaust, or cutouts being full closed.
2nd rev is cutouts being just barely cracked open.
3rd rev is cutouts being full open.
Before you go, please tell us something you want to do to your car…
…but you need a guide to do it.
We will be happy to do it if people need it.