Water Engine

WSM Piston Kit - Kawasaki 300 - +.25 mm 50-255-04K

Regular price ¥15,400 JPY

Very low stock (1 unit)
WSM Piston Kit - Kawasaki 300 - +.50 mm 50-255-05K

Regular price ¥15,700 JPY

Low stock (3 units)
WSM Piston Kit - Kawasaki 300 - +.75 mm 50-255-06K

Regular price ¥15,700 JPY

Low stock (3 units)
WSM Piston Kit - Yamaha 350 - Standard 50-540K

Regular price ¥15,700 JPY

Very low stock (1 unit)
WSM Piston Kit - Yamaha 350 - +.25 mm 50-540-04K

Regular price ¥15,700 JPY

Very low stock (1 unit)
Sold out

WSM Piston Kit - Yamaha 350 - +1 mm 50-540-07K

Regular price ¥15,400 JPY
WSM Piston Kit - Kawasaki 300 - +1 mm 50-255-07K

Regular price ¥15,700 JPY

Low stock (3 units)
Sold out

WSM Piston Kit - Yamaha 350 - +.75 mm 50-540-06K

Regular price ¥15,400 JPY
Sold out

WSM Piston Kit - Polaris 300 - Standard 50-310PK

Regular price ¥14,700 JPY
Sold out

WSM Piston Kit - Polaris Xplorer 300 / Trail Boss 250 +25 mm 50-310-04PK

Regular price ¥14,500 JPY
WSM Piston Kit - Yamaha 350 - +.50 mm 50-540-05K

Regular price ¥15,700 JPY

Low stock (2 units)
WSM Piston Kit - Polaris 300 - +.50 mm 50-310-05PK

Regular price ¥14,700 JPY

Low stock (4 units)
WSM Piston Kit - Polaris 300 - +1 mm 50-310-07PK

Regular price ¥14,700 JPY

Low stock (3 units)
WSM Piston Kit - Polaris 300 - +.75 mm 50-310-06PK

Regular price ¥14,700 JPY

Very low stock (1 unit)
WSM Piston Kit - Honda 420 - Standard 50-231K

Regular price ¥16,800 JPY

Low stock (3 units)
WSM Piston Kit - Honda 420 - +.25 mm 50-231-04K

Regular price ¥16,800 JPY

Low stock (2 units)
Sold out

WSM Piston Kit - Honda 420 - +.50 mm 50-231-05K

Regular price ¥16,800 JPY
Sold out

WSM Piston Kit - Honda 420 - +.75 mm 50-231-06K

Regular price ¥16,800 JPY
Sold out

WSM Piston Kit - Honda 420 - +1 mm 50-231-07K

Regular price ¥16,500 JPY
Sold out

WSM Piston Kit - Yamaha 660 - Standard 50-544K

Regular price ¥18,200 JPY
WSM Piston Kit - Yamaha 660 - +.50 mm 50-544-05K

Regular price ¥18,200 JPY

Very low stock (1 unit)
WSM Piston Kit - Yamaha 660 - +1 mm 50-544-07K

Regular price ¥18,200 JPY

Very low stock (1 unit)
WSM Piston Kit - Yamaha 700 - Standard 50-546K

Regular price ¥19,900 JPY

In stock (11 units)
WSM Piston Kit - Yamaha 700 - +.50 mm 50-546-05K

Regular price ¥19,900 JPY

Very low stock (1 unit)
¥200 off

WSM Piston Kit - Yamaha 80 - Standard 50-536K

Sale price ¥8,900 JPY Regular price ¥9,100

Low stock (3 units)
¥400 off

WSM Piston Kit - Yamaha 80 - +.75 mm 50-536-06K

Sale price ¥8,700 JPY Regular price ¥9,100

Very low stock (1 unit)
Sold out

WSM Piston Kit - Yamaha 700 - +1 mm 50-546-07K

Regular price ¥19,500 JPY
¥200 off

WSM Piston Kit - Yamaha 80 - +.50 mm 50-536-05K

Sale price ¥8,900 JPY Regular price ¥9,100

Low stock (4 units)
Sold out
¥500 off

WSM Piston Kit - Yamaha 80 - +1 mm 50-536-07K

Sale price ¥8,700 JPY Regular price ¥9,200
WSM Piston Kit - Kawasaki 650 - Standard 50-256K

Regular price ¥17,200 JPY

Low stock (3 units)
WSM Piston Kit - Kawasaki 650 - +.25 mm 50-256-04K

Regular price ¥17,200 JPY

Low stock (2 units)
WSM Piston Kit - Kawasaki 650 - +.50 mm 50-256-05K

Regular price ¥17,200 JPY

Low stock (2 units)
Sold out
¥200 off

WSM Piston Kit - Yamaha 80 - +.25 mm 50-536-04K

Sale price ¥8,900 JPY Regular price ¥9,100
Sold out

WSM Piston Kit - Kawasaki 650 - +1 mm 50-256-07K

Regular price ¥15,300 JPY
WSM Piston Kit - Kawasaki 650 - +.75 mm 50-256-06K

Regular price ¥16,900 JPY

Low stock (2 units)
WSM Piston Kit - Kawasaki 750 - Standard 50-258K

Regular price ¥18,800 JPY

In stock (5 units)
WSM Piston Kit - Kawasaki 750 - +.25 mm 50-258-04K

Regular price ¥18,800 JPY

Low stock (2 units)
WSM Piston Kit - Kawasaki 750 - +.50 mm 50-258-05K

Regular price ¥18,800 JPY

Low stock (4 units)
Sold out
¥300 off

WSM Piston Kit - Kawasaki 750 - +1 mm 50-258-07K

Sale price ¥18,400 JPY Regular price ¥18,700
WSM Piston Kit - Polaris 500 - +.25 mm 50-311-04K

Regular price ¥19,000 JPY

Low stock (4 units)
WSM Piston Kit - Kawasaki 750 - +.75 mm 50-258-06K

Regular price ¥18,800 JPY

Low stock (3 units)
WSM Piston Kit - Polaris 500 - +.50 mm 50-311-05K

Regular price ¥19,000 JPY

Low stock (4 units)
WSM Piston Kit - Polaris 500 - Standard 50-311K

Regular price ¥19,000 JPY

Low stock (3 units)
WSM Piston Kit - Polaris 500 - +1 mm 50-311-07K

Regular price ¥19,000 JPY

In stock (13 units)
WSM Piston Kit 50-254K

Regular price ¥25,500 JPY

In stock (5 units)
WSM Piston Kit 50-254-04K

Regular price ¥25,500 JPY

Low stock (2 units)
WSM Piston Kit 50-254-05K

Regular price ¥25,000 JPY

Very low stock (1 unit)
Sold out

WSM Piston Kit 50-254-06K

Regular price ¥25,000 JPY
WSM Piston Kit - Polaris 500 - +.75 mm 50-311-06K

Regular price ¥19,000 JPY

In stock (5 units)
WSM Piston Kit 50-254-07K

Regular price ¥25,000 JPY

Low stock (3 units)

Let customers speak for us

from 670 reviews

Will Be Back!

I recently purchased the Arrow Race-Tech Slip-On Exhaust (Aluminum Dark) for my Kawasaki Z900 (’17–’24), and I couldn’t be happier. The quality is top-tier—lightweight, beautifully finished, and it gives the bike the deep, aggressive sound it should’ve had from the factory. Throttle response feels smoother, and the overall riding experience is noticeably more exciting.

Huge shoutout to Bill from Bills Exhaust. His communication was excellent from start to finish—quick replies, honest info, and genuinely great customer service. The exhaust shipped fast with no delays, no issues, and no backorder nonsense. Exactly what you want when ordering parts for your bike.

If you’re on the fence, go for it. The exhaust is incredible, and Bill makes the whole process even better. Highly recommend!

Brian Brayley

12/01/2025

71856AKN Arrow Race-Tech Slip-on Exhaust, Aluminum Dark for Kawasaki Z900 17-24

Arrived super quick

Arrived super quick, no complaints

Anonymous

11/20/2025

IN STOCK M4 Exhaust GP Black Slip on GSXR600/750 2011-2025 SU6112-GP

Great customer support

Great customer support, fast shipping and delivery , and great quality exhaust . Sounds nice 👍🏼 would definitely recommend

Atticus

11/13/2025

IN STOCK M4 Exhaust GP19 Black Slip On 2009 - 2025 2026 ZX6R zx6 KA6922-GP19

Fast service and the pipe is very well made

Fast service and the pipe is very well made.

72188PD Arrow H.D.1250 Pan America 20-25 Racing St. Steel De-Catalyzed Collector

Purchased the power core 4 along with the mega bomb header

Purchased the power core 4 along with the mega bomb header. Sounds great! Looks even better! Slammed them both on my 22’ KX 250f.

ROBERT T CLARK

11/11/2025

FMF Powercore 4 Muffler KX250F/X 2021-2023 042392 1821-2038

Was trying to find a reseller for Graves products. Stumbled upon this site. No hassles. Ships to Australia (big plus). Now I can mod my dream bike.
Exhaust is gnarly, obnoxious... exactly what I want! Makes all the right sounds.
I'd buy another one if I had another bike.
Super easy fitment, shaved off so much weight with the titanium build.
Absolute piece of art.

Nazzy

11/05/2025

Bill's Exhausts

Great price and amazing sound

Great price and amazing sound.

Michael Adams

10/27/2025

AKRAPOVIC Carbon Fiber Muffler NINJA 400 /500 2018-2025 S-K4SO6-APC 1811-3515

This system with a BT Moto tune sounds and feels amazing

This system with a BT Moto tune sounds and feels amazing. The weight reduction, power increase makes this bike handle even better.
The titanium exhaust system looks amazing.

Lou D

10/19/2025