Honda ST1300 Exhaust Modifications, Exhaust Routing

Honda ST1300 is a remarkable touring motorcycle known for its performance and comfort. One key element contributing to its power and efficiency is the exhaust system.

Let’s look at the specifications of the stock ST1300 exhaust, its design, and how it complies with emission regulations.

Additionally, we’ll explore the exciting world of aftermarket exhaust options, including Delkevic and Staintune.

Honda ST1300 Exhaust Specifications

Stock exhaust is a 4-2-1 stainless steel design with a large catalyst in the muffler. Header pipes are routed on both sides of the engine.

The stock muffler weight is approximately 18 lbs. Aftermarket cans are as light as 6 lbs of carbon fiber.

The header pipe has a diameter of 45mm. The muffler body has a diameter of 50mm. The length of the muffler is 395mm.

Stock exhaust system type: 4-2-1 stainless steel design

Number of header pipes: 4 (2 front, 2 rear cylinders)

Horsepower gain with aftermarket systems: Up to 6 hp more in mid-range

Torque gain with aftermarket systems: Up to 3 lb-ft more torque

Meets EPA, CARB, and Euro 4 regulations with stock or approved aftermarket systems

Exhaust gaskets used: Honda part number 18331-MAJ-000 gasket at cylinder head junction

Sound levels

The stock system is fairly quiet, measuring around 72 dB at wide open throttle.

Approved aftermarket cans range from 74-80 dB.

Honda ST1300 Exhaust Routing

The Honda ST1300 has a 4-2-1 exhaust system design. 4 primary exhaust header pipes merge into 2 pipes, which then merge into 1 final pipe.

There are 4 exhaust ports – 2 for the front cylinders and 2 for the rear cylinders. Each cylinder has its stainless steel primary exhaust header pipe:

  • On the left side, the front cylinder pipe routes rearwards, and the rear cylinder pipe routes forward.
  • On the right side, the front cylinder pipe routes forward, and the rear cylinder pipe routes rearwards.

The left and right side front and rear pipes merge under the engine into 2 collector pipes.

These 2 collector pipes then join together into 1 final outlet pipe. This pipe connects to the catalytic converter and main muffler.

The muffler is located on the right side of the motorcycle.

This 4-2-1 design helps optimize exhaust pulse tuning for engine performance. The layout allows efficient exhaust flow while maintaining street-legal noise levels.

By merging the 4 primary headers into 2 pipes before 1 final outlet, the ST1300 achieves the best balance of power, sound, and emissions control.

Read our linked article for more information on the ST1300’s engine.

Honda ST1300 Aftermarket Exhaust Modifications

Full aftermarket exhaust systems like Yoshimura offer up to 6 hp gain in the mid-range and 2-3 lb-ft more torque.

Slip-on mufflers alone provide modest gains of 1-2 hp and 1 lb-ft of torque typically.

Delkevic and Staintune offer good aftermarket exhaust modifications for the Honda ST1300. The setups usually include exhaust clamp, so there’s no welding required.

Honda ST1300 Delkevic Exhaust

The system is made from stainless steel with carbon fiber end caps on the muffler.

Claimed weight savings over stock is 8.8 lbs, reducing overall weight to just 9.2 lbs. The diameter of the muffler body is 70mm with a 100mm end cap. The piping diameter is 50mm.

The exhaust system produces a deeper, throatier sound than stock but is still road-legal. Dyno tests by Delkevic show gains of 4 hp at high rpm and 3 lb-ft of torque in the midrange.

The exhaust system is designed to work with the stock ECU without re-tuning required.

CARB approval means the Delkevic exhaust system is 50-state street legal in the USA.

Installation requires gaskets, springs, exhaust clamp and exhaust sealant which are included in the kit. The exhaust system is priced at around $1,000 but provides significant weight savings and performance gains.

Delkevic Exhausts for ST1300

Honda ST1300 Staintune Exhausts

Staintune Exhausts are recommended as an alternative to the factory ST1300 exhaust cans due to their superior appearance and sound.

The Staintune system is made of 100% stainless steel, which is highly resistant to high heat and high corrosion demands, especially in urban driving.

The Staintune exhaust features a removable sound restrictor, allowing customization of sound levels.

The Exhaust system has an exhaust clamp. Installation is not too difficult and can be done with a decent set of hand tools in about 20 minutes.

The Staintune exhaust system is significantly lighter than the stock setup, weighing only 13 pounds compared to 26 pounds.

Staintune exhaust modification provides a small increase in horsepower (2-3 hp) but is more about improving the sound.

Tip: Tuning via Power Commander is recommended with aftermarket exhausts to optimize fueling.

Compliance With Emission Regulations

The ST1300 complies with EPA, CARB, and Environment Canada exhaust emissions regulations.

EPA and CARB-compliant slip-ons maintain street legality without re-tuning.

Catalytic converters help meet strict Euro 4 emissions standards on European models.

The ST1300 must comply with EPA noise emission standards, staying under 80 dB at 50 feet at highway speeds.

A catalytic converter is used in the muffler to reduce hydrocarbon, carbon monoxide, and nitrogen oxide emissions.

An oxygen sensor provides input to the ECU to maintain a proper air-fuel ratio for emission control.

The evaporative emissions control system prevents fuel vapor escape by absorbing vapors in a canister.

The vehicle emissions control information label under the seat has specific compliance and tuning specifications.

Note: Exhaust modifications that impact emissions controls like exhaust and air intake changes can violate emissions compliance.

Performance Differences

Delkevic exhaust shows gains of 4 hp at high rpm and 3 lb-ft of torque in the midrange.

Staintune exhaust system provides a small increase in horsepower (2-3 hp) but is more about improving the sound.

Full aftermarket systems like Yoshimura offer up to 6 hp gain in the mid-range and 2-3 lb-ft more torque.

Slip-on mufflers alone provide modest gains of 1-2 hp and 1 lb-ft of torque typically.

Read the linked article on ST1300 Horsepower for a detailed discussion of the engine’s performance.


Honda ST1300 comes equipped with a 4-2-1 stainless steel exhaust system that provides a good balance of power, sound, and emissions compliance.

While aftermarket exhausts can offer modest gains in horsepower and torque along with significant weight reduction, they may require re-tuning to maintain proper air-fuel ratios.

When choosing an aftermarket exhaust, factors like sound profile, emissions legality, ease of installation, and cost should be considered along with potential performance benefits.

Proper tuning and compliance with regulations are important to get the most from an aftermarket exhaust while staying street-legal.

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