FlowFX 409 SS Cat-Back Exhaust System Install – 5th Gen 4Runner

Flowmaster – FlowFX 409 SS Cat-Back Exhaust System, Single Rear Exit Install For the 5th Gen 4Runner

Flowmaster – FlowFX 409 SS Cat-Back Exhaust System, Single Rear Exit Install For the 5th Gen 4Runner

Finally got my hands on a Flowmaster for the 5th Gen 4Runner. This Flowmaster is the FlowFX cat-back exhaust edition.

I drive a 2016 SR5 Premium as my daily driver with about 50k miles on it. After doing research, and by research, I mean reading the articles posted on the 5th Gen Performance mods page. I noticed that Flowmaster discontinued their exhaust system for the 5th Gen 4Runner. After contacting them, I discovered they recently started selling a new system, the Flowmaster FlowFX 409 SS.

I was looking for an exhaust system that would give me that aggressive sound and performance (mostly sound) but nevertheless I found what I was looking for.

It is stated on the Flowmaster website, this exhaust system gives you 5.3 more HP and 4.7 ft of Torque.

A cool thing about this system is that it comes with blacked-out tips straight out of the box, since everyone hates chrome, they do you the favor.

This system is available online in 2 places, Carid.com and Holley.com. Both for the same price. The only difference was the lead times. I’ve had my eyes on this system for about 2 months but finally got an email saying they were in stock and ready to ship.

Find it online

  • Flowmaster FlowFX409 SS Cat-Back Exhaust System (From Carid.com): Check Price
  • Flowmaster FlowFX 409 SS Cat-Back Exhaust System (From Holley): Check Price

Let’s get started!

Flowmaster FlowFX 409 SS Step-By-Step Install

The install took a total amount of 2.5 to 3 hours.

Disclaimer: I have no experience working on cars besides growing up watching family work on cars. Needless to say, I did this with minimal tools and without a jack to raise the car. After two trips to the auto store and the emotional support of my girlfriend, we got it done. If you want to see another exhaust install process with better photos, you can see the Borla install here.

Tools & Materials

  • Nitrile Gloves
  • Anti-Seize Lubricant
  • WD-40
  • Metric Sockets: 14, 15, 16 mm
  • Long & Short Handle Ratchet

What’s in the Box?

Flowmaster – FlowFX 409 SS Cat-Back Exhaust System, Single Rear Exit Install For the 5th Gen 4Runner

The box from Flowmaster comes with all of the hardware needed for this project.

Upon opening the box, the stainless steel parts feel so light yet very sturdy. The parts are welded and feel durable.

The kit includes:

  • FlowFX Muffler (separate box)
  • 2 ½ Stainless Steel Band Clamps with 17mm bolts (x3)
  • Washers
  • Lock Washers To Connect

Flowmaster also throws in a good amount of stickers. The FlowFX Muffler comes in a separate box bubble-wrapped for protection.

Step 1. Remove Stock Factory System

Flowmaster – FlowFX 409 SS Cat-Back Exhaust System, Single Rear Exit Install For the 5th Gen 4Runner

The first thing I suggest doing, especially if you are doing this with no jack or stands, is to remove the spare tire. Having the extra space is definitely needed especially when removing the tailpipe.

Also, with any factory bolts being removed and reused along with the clamps, I applied Anti-Seize Lubricant. You don’t need a gallon; they sell small packs at O’Reilly for $1.60.

The next step is to unbolt the tailpipe. The bolts measure 14mm but may differ. These bolts were a pain to take off. Not too sure if all 4Runners are like this, but mine was welded on the bottom so I had to remove them from the top using a long handle wrench. For this specific exhaust system, these bolts are not used again.

Next, remove tailpipe hanger from rubber mounts

Once you unbolt the two bolts, remove the tailpipe hanger from the rubber mounts. This is where WD-40 is your best friend. The hangers-on my 4Runner were stuck pretty well in there (maybe from all the mud) but after a good amount of sprays and some force they slipped off. Wiggling out the tailpipe was probably the most frustrating part of this whole process. Just be patient and it will come out.

Next is removing the 2 factory spring-loaded bolts (15mm) at the inlet pipe flange connection. These bolts come off easily. Save these 2 bolts since you will be needing them again.

Now, after removal of the 2 spring-loaded bolts, the only support holding the muffler and front pipe, are 4 rubber isolator mounts (identical to the one holding up the tailpipe). WD-40 those up and slide them off, just be careful since the stock muffler is pretty heavy and drops with some good force.

Step 2. Install Flowmaster

Flowmaster – FlowFX 409 SS Cat-Back Exhaust System, Single Rear Exit Install For the 5th Gen 4Runner

Flowmaster has you start by connecting the inlet pipe to flanges using the 2 factory spring-loaded bolts. Remember to apply the anti-seize lubricant on these bolts. After evenly tightening those up, slide the hangers into the rubber mounts.

Next is connecting the FlowFX muffler.

Before connecting the muffler, place the clamps on both ends of the muffler. Slide the FlowFX into int inlet pipe and tighten the front clamp. Don’t over tighten the clamp just yet.

Once the FlowFX muffler is in place, route the tailpipe over the axle and connect it to the FlowFX Muffler. Place the clamps onto the exit pipe and assembly and connect it to the over axle pipe. Tighten the clamps but allow room for adjustments.

Step 3. Final Adjustments

Flowmaster – FlowFX 409 SS Cat-Back Exhaust System, Single Rear Exit Install For the 5th Gen 4Runner

I went back and made sure all bolts were tight and secure, the clamps were nice and sturdy and all hangers were in the rubber mounts. I went ahead and made sure the tailpipe was not touching any components.

Now for the glorious moment: Key in, turn it on and listen to the aggressive pur Flowmaster is known for.

Following my small moment of feeling victorious, I went under the truck again to make sure no unusual noises or rattling were occurring. After making sure everything was tight and secure, it was time for a test drive.

After the first drive around the neighborhood, I brought the truck back gave it a few revs now that the truck was warm and I couldn’t be happier.

I suggest driving the new exhaust for a good 25-35 miles and going back under and making sure everything is still secure and nothing has moved.

Final Thoughts

I am going on a month now with the Flowmaster, and with no hesitation, I can say I love this system!

The blacktip really suits my truck nicely. The number of compliments I get about the sound really makes me feel proud of my decision.

Cabin noise is obviously noticeable from stock but it’s exactly what I was looking for. City driving gives you a deep and aggressive per and definitely turns heads. High acceleration, such as entering a freeway or uphill, is the loudest amount of noise. To me, the amount of cabin noise is not annoying or obnoxious, but it actually gives a sense of satisfaction.

One thing I would say about the exhaust is that it does sit a bit low. I may need to do some readjustments to try and raise it up a bit for clearance.

Would I choose this system again if I had the option to go a different route? ABSOLUTELY.

Not only is the sound exactly what I’m looking for but the black tip it comes with is just the perfect finisher. Thankful to Flowmaster for making such a great product for the 5th Gen 4Runner.

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3 years ago

I also did this install in June 2020, Holley offers Veterans discounts, I believe it was 10%, but you will have to speak with someone, the website did not have the option.

3 years ago

I hope someone can do a review of the Magnaflow overland exhaust! This sounds great though!

E Mansur
E Mansur
3 years ago

How’s the gas mileage? Any improvements?

3 years ago

It is NOT a good idea to free up rubber exhaust hangers with WD-40 if you plan to reuse them. WD-40 contains petroleum distillates that will breakdown the rubber composition of the hanger and dramatically shorten their service life. Instead use silicone spray lubricant in order to achieve the same effect without damage to the rubber. It’s also worth noting that Lisle Tools makes affordable exhaust hanger pliers to separate the hangers from the exhaust but slip joint pliers will also work with a little extra effort along with a mindful approach.

3 years ago

Nice write up! I got this installed in October and I love it! It had mellowed out a bit…and then I put on a y pipe and headers…now it screams! Glad you love it as well!

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