CRF300L / Rally Yoshimura RS-12 Exhaust: Full System vs. Slip-On

RS-12 full system versus slip-on: price and scope

These prices apply to the linked CRF300L and Rally listings as checked. Prices can change; confirm the current product price and any applicable tax or shipping at checkout. Allow separately for installation and any other work your build requires.

Both configurations use stainless-steel exhaust construction and a stainless muffler, with a supplied matte carbon-fiber heat shield. The full system adds Yoshimura's header to the package. A slip-on purchase does not include that replacement header.

Keep the weight comparisons on the same basis

The slip-on's 7.3 lb figure excludes the retained stock header. Comparing 7.3 lb directly with the complete system's 9.0 lb would mix different assemblies. Use each row's matching stock reference to understand the change.

Choose the listing for your CRF300L or Rally

Our current product fitment covers 2021–2027 CRF300L and CRF300L Rally through the model-specific listings below. Check your exact model and year before ordering.

• CRF300L: RS-12 full system or RS-12 slip-on.
• CRF300L Rally: RS-12 full system or RS-12 slip-on.

Yoshimura develops these products around U.S.-market, factory-equipped motorcycles. If you have a non-U.S. bike, a CRF300LS, or accessories near the exhaust, confirm compatibility with us before purchasing. Include the model year, country specification and any changes to the bike.

What do the RS-12 power claims actually tell you?

Yoshimura publishes the following comparisons with a spark arrestor fitted:

• Full system: up to 6.8% more horsepower at 8,520 rpm and 4.3% more torque at 6,600 rpm.
• Slip-on: up to 7.0% more horsepower at 5,000 rpm.

These are manufacturer-reported results at the specified engine speeds. They are not CRF's Only dyno measurements or a guarantee of the same gain on every motorcycle.

In particular, 7.0% at 5,000 rpm does not prove that the slip-on makes more power than the full system. The headline percentages describe different points on the engine's operating range. They also do not establish a 6.8% or 7.0% improvement everywhere, a specific absolute horsepower increase, or the fueling setup your bike needs.

Choose the configuration around the complete build, installation scope and budget. Use the published numbers to understand Yoshimura's claims without turning a single test point into an across-the-board promise.

Sound, the included spark arrestor and the optional insert

Yoshimura's current slip-on page publishes the following sound comparison under its stated J2825 test conditions, with the SA-20-K spark arrestor installed.

The slip-on is louder than stock in both reported measurements. These figures apply to that tested slip-on configuration; they are not full-system readings or measurements with a different insert. They also do not guarantee a pass under a competition organizer's different test method or limit.

Both exact RS-12 product pages and their installation parts lists identify SA-20-K as installed and INS-34-K as an optional sound insert. The optional insert is not included. Keep those part numbers tied to the correct exhaust when ordering replacements.

A spark arrestor and a sound insert serve different purposes. Neither changes these products' closed-course-only designation. For replacement parts or help choosing an insert, send us your exhaust part number.

Plan the installation before opening the toolbox

Use the instructions for your exact part number and work on a cool, securely supported motorcycle. A slip-on retains more original parts, but it still has application-specific fitting steps.

• Full system: the instructions transfer the stock oxygen sensor to the Yoshimura tailpipe. Inspect the exhaust-port gasket and replace it if needed. The Rally has additional bodywork-removal steps.
• Slip-on: the instructions call for trimming the inner bottom tab of the right side panel for tailpipe clearance. They also specify that the stock exhaust joint gasket is not reused.
• Both: follow the specified assembly sequence, check clearance and use the applicable factory torque specifications.

Read the 123410S520 full-system instructions or 123412S520 slip-on instructions before deciding whether to install it yourself or use a qualified mechanic.

Match fueling advice to the actual motorcycle

Before ordering a fuel controller or arranging ECU work, tell us your model year, intake configuration, existing tuning and chosen exhaust. Have the fueling requirements assessed for that combination. Exhaust fitment and published dyno gains alone do not establish whether your bike needs a fueling change.

Our CRF300L Rider Guide and CRF300L Rally Rider Guide help connect the exhaust decision with the rest of the build.

Include muffler maintenance in the plan

Follow Yoshimura's packing and fastener inspection guidance. The supplied instructions recommend repacking at least annually, with more frequent service possible depending on use. Increasing sound or visible deterioration calls for inspection; the original sound figures are not a lifetime guarantee.

Which RS-12 purchase makes sense?

• Choose the full system when replacing the header is part of your plan and you want the complete matched assembly in one purchase.
• Choose the slip-on when retaining the factory header suits the build and the lower initial price matters.
• Already own an RS-12 slip-on? Review the conversion option before purchasing another muffler.

Converting an existing RS-12 slip-on

The Yoshimura RS-12 header, mid-pipe and springs kit is listed at $469.99 as checked October 24, 2026. It converts the compatible existing RS-12 slip-on to a full system and does not include a muffler. Confirm the exact application before ordering.

Buying the $749 slip-on and $469.99 conversion kit at these prices totals $1,218.99 in parts, compared with $849 for the complete system. If a full system is your goal from the start, buying it together costs $369.99 less before tax, shipping and installation.

CRF's Only can help you compare the purchase paths and identify the correct model listing. Tell us what is already on the bike so the next purchase builds on the parts you own.

CRF300L Yoshimura RS-12 questions

How much does a CRF300L Yoshimura RS-12 cost?

Prices checked October 24, 2026 were $849 for the full system and $749 for the slip-on in the linked CRF300L and Rally listings. Check the product page for current pricing.

How much weight does the RS-12 save?

Yoshimura's figures give a 3.3 lb saving for the full system and a 2.7 lb saving for the slip-on compared with their matching stock components. The slip-on figure excludes the stock header that stays on the bike.

Does it include a spark arrestor?

Yes. The exact full-system and slip-on documentation lists the SA-20-K spark arrestor as installed. The INS-34-K sound insert is optional and not included.

Can I use these RS-12 versions on the street?

No. The featured Race Series products are designated for closed-course competition only. The installed spark arrestor does not provide street-use or public-land approval.

Does the slip-on need a replacement header?

The slip-on attaches to the stock header. A compatible RS-12 header and mid-pipe conversion is available separately if you later choose a full-system configuration.

Does the same exhaust fit the CRF300L Rally?

Yoshimura lists both CRF300L and Rally applications. Use the Rally-specific product links above and confirm your year and market specification; Rally bodywork affects installation access.