Flowmaster 3IN (O)/OUT (O) 40 Series Muffler

Flowmaster's Original 40 Series muffler, part number 43043, for the 2011-2014 Mustang GT and the 2012-2013 Boss 302. This is the muffler that makes the original Flowmaster sound, and Flowmaster says the tone is aggressive outside the car and inside it too.

Why Upgrade to a 40 Series Muffler

Per Flowmaster, here is what this muffler brings:

• That original Flowmaster sound. If that is the tone you have been chasing, this is the muffler that makes it.
• An aggressive exterior tone. People hear you coming and they hear you leave.
• An aggressive interior tone as well. You hear it from the driver's seat, not just from the curb.
• A 16 gauge aluminized steel body, fully MIG welded, for maximum durability.

Fitment Notes

Fits the 2011-2014 Ford Mustang GT and the 2012-2013 Mustang Boss 302. Does not fit the GT500 or the V6 Mustang. The title lists this muffler as 3IN (O)/OUT (O), so confirm the inlet and outlet match your exhaust pipe diameter and routing before you order. [VERIFY: whether (O) means offset inlet and offset outlet, and that a 3 inch pipe matches your setup.]

More Mufflers that fit your Mustang

Install and Honest Talk

Honest talk: an aggressive interior tone means you will hear this muffler in the cabin on the highway, not just at the stoplight. If you want a quiet cruise, know what you are signing up for. The source copy says nothing about how the muffler goes on, whether it clamps or welds in, what comes off the stock exhaust, or whether it sits in the factory location, so read the included instructions before the car goes on the lift. [VERIFY: install method, clamps or welding, what comes off the stock exhaust, and whether it fits the factory hangers and pipe routing.] What else you need: check the included instructions for whether clamps, hangers, adapters or welding are required.

Specs

• Brand: Flowmaster
• Part number: 43043
• Part type: Muffler
• Series: Original 40 Series
• Inlet/outlet: 3IN (O)/OUT (O), as listed in the title
• Material: 16 gauge aluminized steel
• Construction: Fully MIG welded
• Quantity: [VERIFY: one muffler per part number]

Swipe sideways to see the full table

Free US shipping over $99

Orders over $99 ship free by ground to the lower 48 states. Alaska, Hawaii and Canada are not included; shipping to those addresses is calculated at checkout. Some oversize or heavy parts (long-tube exhausts, bumpers, full lift kits) go freight instead of parcel: free to a commercial address with a loading dock, and residential freight delivery carries an additional charge.

When it ships

Parts ship direct from the distributor warehouse that stocks them, so dispatch timing depends on the part, not on a single cutoff. You get a confirmation with tracking as soon as it leaves, and tracking shows the delivery estimate for your address. If a part is backordered we email you an expected availability date.

Missing or damaged items

Report a short shipment or shipping damage within 5 business days of delivery. For a packing error, send us the date or package code printed on the label along with the part number so we can trace it with the warehouse.

We have a 30-day return policy, which means you have 30 days after receiving your item to request a return.

To be eligible for a return, your item must be in the same condition that you received it, unworn or unused, with tags, and in its original packaging. You’ll also need the receipt or proof of purchase.

To start a return, you can contact us at help@anythingcoyote.com or fill our our contact form. If your return is accepted, we’ll send you a return shipping label, as well as instructions on how and where to send your package. Items sent back to us without first requesting a return will not be accepted. 

You can always contact us for any return question at help@anythingcoyote.com.

Damages and issues
Please inspect your order upon reception and contact us immediately if the item is defective, damaged or if you receive the wrong item, so that we can evaluate the issue and make it right.

Exceptions / non-returnable items
Certain types of items cannot be returned, like perishable goods (such as food, flowers, or plants), custom products (such as special orders or personalized items), and personal care goods (such as beauty products). We also do not accept returns for hazardous materials, flammable liquids, or gases. Please get in touch if you have questions or concerns about your specific item.

Unfortunately, we cannot accept returns on sale items or gift cards.

Exchanges
The fastest way to ensure you get what you want is to return the item you have, and once the return is accepted, make a separate purchase for the new item.

Refunds
We will notify you once we’ve received and inspected your return, and let you know if the refund was approved or not. If approved, you’ll be automatically refunded on your original payment method. Please remember it can take some time for your bank or credit card company to process and post the refund too.