Mustang EcoBoost Downpipe Install

Installing a new downpipe on your S550 Mustang EcoBoost is an effective way boost horsepower and allow for your exhaust gases to flow more efficiently. However, be aware that your EcoBoost will require a tune because of the increased exhaust flow. Also, installing a catless downpipe could make your Mustang illegal in some states. Always check your state's regulations before making major exhaust modifications.

Even if you're new to working on cars, installing an aftermarket downpipe on your Mustang EcoBoost is easy. These step-by-step instructions will walk you through the installation process.

Mustang EcoBoost Downpipe Install Instructions

In the video, we're installing a Mishimoto high-flow catted downpipe, but you can expect the steps to be similar for any Mustang downpipe.

Parts and Tools Needed:

Step 1: Remove Upper O2 Sensor

Locate the upper O2 Sensor and the wire attached to it. It's on the left side of the engine closest to the firewall.

Follow the sensor cable up and unplug it.

Step 2: Disconnect Downpipe from Turbo

Important: Before removing the downpipe, make sure the engine is cold. The downpipe gets extremely hot and can burn you if you're not careful.

Locate and remove the two bolts connecting the downpipe to the turbo.

The top bolt is easier to remove from the top of the car, while the bottom one is easier to get to from underneath the car.

Step 3: Loosen Nuts on Resonator Sleeve

Loosen the two nuts on the sleeve that connects the downpipe to the factory resonator.

Step 4: Disconnect Downpipe from Resonator

Slightly bend the tab on the back of the sleeve connecting the downpipe to the factory resonator. Then, slide the sleeve off the downpipe, disconnecting the two.

Step 5: Disconnect Downstream O2 Sensor

Locate the downstream O2 sensor on the side of the transmission and disconnect it.

Also, detach the metal clip above the O2 sensor to fully remove it.

Step 6: Unhook Exhaust from Exhaust Hanger

Using the exhaust hanger removal tool, unhook the exhaust from the hanger.

Step 7: Remove Bracket on Side of Transmission

Using a ratchet, undo the bolts on the bracket holding the downpipe to the transmission.

After this, you should be able to pull the factory downpipe out from underneath the car.

Reminder: Be sure to hold on to the stock gasket since you'll need it to install the aftermarket downpipe.

Step 8: Install Components on New Downpipe

Before reinstalling your downstream and upstream O2 sensors, put antiseize on the threads to help with installation.

Using your O2 sensor wrench, reinstall the two factory O2 sensors in their correct positions on the new pipe.

Install the factory mounting bracket using the factory hardware. Be sure that you don't tighten the nuts down fully since you'll need to adjust positioning slightly while on the car.

Step 9: Reattach Gasket to Turbo

Reattach the stock gasket that you saved from earlier to the turbo with the seals facing inward.

Step 10: Seat Your New Downpipe

Hold the downpipe in place against the gasket. While still holding the downpipe, tighten down the mounting bracket with the two factory bolts until they're finger-tight.

Step 11: Reconnect Front Pipe to Turbo

Reinstall the two bolts where the front pipe and turbo meet and tighten them down with a ratchet.

The top bolt is easier to tighten from the top of the car, while the bottom one is easier to get from underneath.

Step 12: Connect Secondary Pipe to Front Pipe

Slide the collar over the front pipe first and then slide the secondary pipe over the front pipe.

Next, spin the secondary pipe into place and connect it to the exhaust hanger.

Finally, slide the collar over where the front and secondary pipes connect without tightening it.

Step 13: Connect Secondary Pipe to Resonator

Install the adapter provided onto the resonator. It should slide into place and bottom out before going all the way into the pipe.

After it's bottomed out, slide the provided band clamp over the secondary pipe and adapter and tighten it down with your ratchet.

Finally, slide the collar over where the resonator and adapter connect and tighten the two nuts.

Step 14: Tighten Remaining Bolts and Reconnect O2 Sensors

Return to the collar where the front pipe and secondary pipe connect and tighten it down fully with a ratchet.

Next, fully tighten the bolts on the mounting bracket that we left finger-tight earlier.

Finally, reconnect both the upstream and downstream O2 sensors.

Congratulations, you're all done!

Make the Most of Your Ford Mustang EcoBoost's New Downpipe

WIth your newly installed downpipe on your EcoBoost Mustang, you can expect an increase in horsepower after you add a custom tune. If you're looking for a way to improve engine airflow to get your EcoBoost breathing as well as it can, consider adding a cold air intake as well.