Yoshimura MT-09 AT2 Speed Series Full System Preview

49-state AT2 full system sheds 4.9 lb for $1,199

The Short Answer: The Yoshimura MT-09 AT2 Speed Series Full System (part #13992SP520) is a stainless-steel full exhaust for the 2021-26 Yamaha MT-09, 2022-25 XSR900 and 2021-22 Tracer 9 GT. Yoshimura says it’s 49-state emissions compliant, weighs 10.7 pounds versus 15.6 for stock, adds up to 3.1 percent more horsepower and costs $1,199, with deliveries starting at the end of October.

We’ve bolted a lot of pipes onto a lot of motorcycles, and the hardest part usually isn’t the install. It’s wondering whether I’m one traffic stop away from an awkward chat about the Clean Air Act. Yoshimura’s new AT2 Speed Series full system for Yamaha’s MT-09 answers that question better than most race-bred pipes, at least outside California.

The AT2 full system for the MT-09 isn’t new. Yoshimura calls its AT2 Race Series version “one of our most popular systems.” What’s new is a Speed Series version, Yoshimura’s emissions-friendly line, with the same AT2 looks and sound. It’s designed, developed and built in Chino, California.

What Is the Yoshimura MT-09 AT2 Speed Series Full System?

It’s a complete header-to-muffler replacement for the stock exhaust on Yamaha’s 890cc CP3 inline-triple platform. Yoshimura’s official listing calls it the “MT-09 21-26 / XSR 900 22-25 Speed AT2 Stainless Full Exhaust, w/ Stainless Muffler.” The release describes it as stainless steel with a stainless muffler, a carbon-fiber end cap and Yoshimura’s Works Finish.

The design has a Works Finish stainless header with Yoshimura’s Integrated Sonic Chamber, which feeds the company’s AT2 muffler. Yoshimura credits the Integrated Sonic Chamber with boosting power over the stock system, adding “a little extra bark” and keeping the Speed Series system “49 state friendly.” The end cap is carbon fiber.

Yoshimura also says the system is “Euro 5+, dual lambda compatible.” Lambda is engineer-speak for the oxygen sensor. Euro-spec bikes use two of them, and the kit includes two O2 sensor bung adapters to cover both setups. According to Yoshimura’s instruction sheet, U.S.-spec bikes run their single O2 sensor in the forward bung on the collector, while EU-spec bikes use both the front and rear bungs.

Speed Series vs. Race Series: What’s the Difference?

This is the part most buyers care about, so let’s be clear. Yoshimura sells two AT2 full systems for this Yamaha platform at the same price:

• AT2 Race Series (part #13992AP521): $1,199 on Yoshimura’s site. Claimed weight is 9.6 pounds, and Yoshimura claims gains of 2.7 percent in max horsepower and 1.6 percent in max torque. Yoshimura’s warning for Race Series products says they bypass required emissions control elements and are for closed-course competition only.
• AT2 Speed Series (part #13992SP520): $1,199. Claimed weight is 10.7 pounds, with up to 3.1 percent more horsepower at 9,000 rpm. Yoshimura’s instruction sheet says Speed Series systems are 49-state emissions compliant but not CARB tailpipe-emissions compliant.

So the Speed Series carries 1.1 pounds more than the Race Series. Yoshimura doesn’t say why. Its power claim is a little higher, but that isn’t an apples-to-apples comparison. The Race Series numbers come from Yoshimura’s original 2021 MT-09 development, and the Speed Series dyno chart is labeled “2026 Yamaha MT09.”

The fine print matters if you live where I do. Yoshimura’s product page and instruction sheet both say the Speed Series system is “for closed course competition only; not intended for street use in California.” The instruction sheet also lists the system as a Qualified Manufacturer Declared “Modified Part.” Translation: if your plate says California, this isn’t your street-legal ticket.

Performance: Power, Torque and Weight Claims

Yamaha’s CP3 already has plenty of torque. Yoshimura says its engineers are “squeezing every drop” from the 890cc triple. Here are the claims:

• Horsepower: Up to 3.1 percent more at 9,000 rpm versus the stock system.
• Torque: Yoshimura’s release text and product description claim up to 3.8 percent more at 6,800 rpm. The dyno chart in the same release reads +3.3 percent at 6,800 rpm. Either way, it’s a modest single-digit bump.
• Weight: 10.7 pounds for the AT2 Speed Series full system versus 15.6 pounds for stock, a 4.9-pound (about 31 percent) cut.

Will you feel 3 percent in the seat of your pants? About as much as you’d feel me skipping a second breakfast burrito. The weight loss is easier to notice, and the sound is what really sells it.

Sound Levels

Yoshimura published sound figures measured to the SAE J2825 standard, with no sound insert installed:

• 2,000 rpm: 93.8 dB for the AT2 full system versus 83.4 dB for stock, a 10.4 dB increase.
• 5,000 rpm: 99.8 dB versus 98.2 dB for stock, a 1.6 dB increase. The release and product page label the 99.8 dB figure “RS-9T,” which looks like a typo carried over from another product sheet. It sits in the AT2’s spec block.

In plain English, the AT2 adds most of its extra noise at low revs, like idling at the coffee shop. For anyone who wants it quieter, Yoshimura lists two optional sound inserts, INS-20-K and INS-27-K. Neither is included. Your neighbors may want to chip in for one.

What’s in the Box

Yoshimura’s instruction sheet lists the full kit, and it’s thorough:

• Works Finish stainless header (13993-401C) and AT2 muffler (13992AP520-RMA)
• Tailpipe bracket that mounts with the stock oil pan bolts, plus a dedicated muffler bracket with a rubber grommet and aluminum spacers
• Two O2 sensor bung adapters, an O2 sensor extension wire and an O2 bung plug
• Mounting hardware, a small spring, a cable tie and a spring puller tool

Service parts include an AT2 repack kit (REPACK-AT2-ADV) and a replacement end cap kit (YM5-1-CFR-K). Yoshimura recommends repacking the muffler at least once a year, more often if you ride hard. Ask me how I know.

Works Finish Explained

Works Finish is Yoshimura’s satin/matte treatment for stainless steel. After a heat cycle on the bike, it takes on colors that Yoshimura says look “much like those titanium works components our factory racers use.” Yoshimura says the finish has uniform heat coloration, increased fatigue strength and better scratch and stain resistance.

Before the first start-up, wipe the system down with rubbing alcohol to remove oil and fingerprints. The color changes after a heat cycle of 15 minutes or more. Never use abrasives or polish on Works Finish. Yoshimura recommends Bar Keepers Friend for minor stains, so keep the kitchen scrub pad far away.

Fitment and Installation Notes

According to Yoshimura’s release and official fitment list, the system fits:

• 2021-2026 Yamaha MT-09
• 2022-2025 Yamaha XSR900
• 2021-2022 Yamaha Tracer 9 GT (centerstand removal required)

Yoshimura says it was designed and tested for U.S.-market bikes in stock factory trim, and OE or aftermarket accessories not on the bike from the factory may not fit with it. The stock exhaust port gaskets get reused, so inspect them first, and the new tailpipe bracket bolts on with the two right-rear oil pan bolts.

One hard-earned tip: plug that O2 sensor back in. On our Yamaha YZF-R9 Real MC Commute, which uses the same CP3 engine family, we forgot after an exhaust install and got a holiday light show on the dash. Learn from our mistakes. That’s what we’re here for.

Yoshimura MT-09 AT2 Speed Series Full System Specifications

Price, Availability and Where It Fits

The Yoshimura MT-09 AT2 Speed Series Full System has a $1,199 MSRP. Yoshimura’s release promises delivery at the end of October, and its official product page lists it for pre-order. Like every Yoshimura R&D of America exhaust, it has a one-year limited warranty against defects in workmanship and materials for the original purchaser.

It costs the same as the Race Series AT2 full system. For street riders outside California, the choice is easy: give up 1.1 pounds and get a system Yoshimura calls 49-state emissions compliant. That’s a good trade for less legal worry.

If you’ve read our 2026 Yamaha MT-09 SP Review, you know the MT-09 has never lacked personality. The AT2 doesn’t change that. It just turns the volume up, especially at low rpm. Yoshimura’s AT2 also isn’t new to Moto-1. We fitted the AT2 Street Series 3/4 system to a Kawasaki Ninja ZX-6R in our Yoshimura AT2 Exhaust Review, and its RS-2 full system woke up a small dual-sport in How $650 and 30 Minutes Transformed Our 2026 Yamaha WR125R.

The Bottom Line

The Yoshimura MT-09 AT2 Speed Series Full System brings the AT2’s sound, looks and Chino-made quality to a 49-state emissions-compliant package. It’s 4.9 pounds lighter than stock and costs the same $1,199 as the Race Series version. California riders should note the street-use restriction. For everyone else with a 2021-26 MT-09, 2022-25 XSR900 or 2021-22 Tracer 9 GT, it’s one of the easiest ways to add bark and drop weight without the legal headache.

Related Moto-1 Reading

• 2026 Yamaha MT-09 SP Review: Our take on the top-shelf version of the bike this pipe fits
• Yoshimura AT2 Exhaust Review: The AT2 3/4 system on Kawasaki’s Ninja ZX-6R
• Yamaha YZF-R9 Real MC Commute: The same 890cc CP3 triple in sportbike form
• How $650 and 30 Minutes Transformed Our 2026 Yamaha WR125R: A Yoshimura RS-2 full system install, step by step

Yoshimura MT-09 AT2 Speed Series FAQ

How much is the Yoshimura AT2 Speed Series full system for the MT-09?

$1,199 MSRP for part #13992SP520, the same price as the AT2 Race Series full system.

When is it available?

Yoshimura says deliveries start at the end of October. Its website lists the system for pre-order.

Is the AT2 Speed Series street legal?

Yoshimura says Speed Series systems are 49-state emissions compliant but not CARB tailpipe-emissions compliant, and this one is not intended for street use in California.

Which bikes does it fit?

The 2021-26 Yamaha MT-09, 2022-25 XSR900 and 2021-22 Tracer 9 GT. The Tracer 9 GT’s centerstand must be removed.

How much weight does it save?

Yoshimura lists 10.7 pounds versus 15.6 pounds for the stock system, a 4.9-pound savings.