Fuel X: Worth Using? (Two years + On The Bike)

Fuel X Lite Review — KTM 390 Adventure

The reviewer tested the Fuel X Lite on a 2020 KTM 390 Adventure fitted with a full Dominator exhaust system, replacing the stock catalytic converters, midpipe, and muffler.

Main Features and Results

• Smoother low-RPM throttle: This was the clearest benefit. The throttle felt less jerky below roughly 3,500–4,000 RPM, where the reviewer says the engine naturally feels rough. The improvement was noticeable and consistent.
• Low-end torque: The reviewer noticed no meaningful torque gain. A rear sprocket with three extra teeth had previously made the bike feel torquier, and the Fuel X did not make up for that difference after the reviewer returned to stock gearing. For more torque, the reviewer suggests dropping one tooth on the front sprocket, which costs about $13.
• Power and acceleration: The reviewer noticed no clear increase in power or acceleration. Any gain, in his view, would be very subtle.
• Engine temperature: Fuel X claims the engine will run cooler. The reviewer thinks this may be technically true because the system makes the engine run less lean, but he saw no noticeable temperature change on the dash. His bike also had no overheating problems during slow off-road riding, hill climbs, or extended high-speed trips.
• Full exhaust compatibility: Some exhaust makers recommend a fuel tuner with a full system; Dominator said its system did not require one. The reviewer noticed no performance loss after removing the stock catalytic converters, but notes that other manufacturers may have different requirements. At about $150, and sometimes less, he considers the Fuel X a relatively inexpensive option if a tuner is recommended or provides peace of mind.
• Slip-ons or resonator removal: The reviewer doubts those changes alone create enough difference in back pressure to make a Fuel X necessary. He also questions how much back pressure the stock resonator creates, while acknowledging that the catalytic converters could contribute some.

Pros

• Noticeably improves low-speed throttle smoothness.
• Makes the bike feel better during everyday acceleration.
• Relatively inexpensive compared with other fuel-tuning options.
• May provide reassurance when fitting a full exhaust system.

Cons

• No noticeable torque, acceleration, or power improvement in the reviewer’s experience.
• No significant, observable cooling benefit.
• Probably unnecessary with a stock exhaust—or for a rider who is not bothered by the low-RPM throttle behavior.

Verdict

The reviewer recommends the Fuel X Lite if the rider dislikes the KTM 390’s low-RPM throttle jerkiness. At around $150, the smoother response may make the bike feel better every time it accelerates.

He also recommends considering it with a full exhaust system, particularly when the exhaust manufacturer advises using a fuel tuner. He would not buy it solely for more torque, power, or cooler running, or for a stock exhaust if the throttle already feels fine.

Rating: No formal score or rating is given.

Different Views and Claims

• Fuel X’s stated claims, as reported by the reviewer: Smoother throttle, more bottom-end torque, and cooler engine operation.
• Reviewer’s experience: The throttle-smoothing claim held up; torque and cooling benefits were not meaningfully apparent, and he noticed no significant power increase.