We understand where this comes from. Sound is not just decibels, it's the feeling of being on a motorcycle. It's your identity on the road. So here's an explanation of what's happening, and where things stand today.
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Your ride back
18
Jun '26
Dr. Jekill & Mr. Hyde | News
Since the introduction of stricter Euro 5+ noise regulations (R41.05), some riders have been wondering whether their Dr. Jekill & Mr. Hyde exhaust still delivers the experience they pay for. There is a perception that the valve seems to intervene more often than on older systems. And a fair question has come up: Is it still worth it?
What changed and why
The R41.05 regulation, issued by the European Economic Commission, was the most significant shift in motorcycle noise legislation in years. Sound cameras were being introduced, fines increased, and enforcement is got stricter by the day across Europe. Unlike previous standards, the R41.05 regulation doesn't only measure sound at a standstill or at full throttle. It measures your motorcycle continuously at speeds between 10 and 100 km/h. In other words, exactly how you ride every day. Every certified exhaust system on a Euro 5+ motorcycle must comply.
Video: Meet Sabrina. Dr. Jekill & Mr. Hyde's riding robot.
What Dr. Jekill & Mr. Hyde does for you
We didn't accept stricter limits and simply deliver a quieter exhaust. We invested in our own state-of-the-art test lab, running continuous measurements 24/7 using our test robot Sabrina: emission tests, durability tests, and sound measurements under tightly controlled conditions. The goal has always been the same: get you as close to the maximum legal sound level as possible, at every moment you're riding.
The Smartbox — with custom-made software developed for each individual motorcycle model — is the brain behind this. Combined with our Fast Valve Response servo motors that react within a millisecond, the valve continuously positions itself to give you the most sound the law allows. Not a fixed setting. Not a blunt cut-off. A system that's always working in your favor.
Video: Dr. Jekill & Mr. Hyde's revolutionary valve system.
Is the experience still there?
Stricter legislation means a lower ceiling for every certified exhaust on the market. Within that ceiling, our systems extract everything that's legally possible — three sound modes, Fast Valve Response servo motors reacting within a millisecond, and a Smartbox with custom software for each individual model. A system that maximizes rather than merely manages.
No other exhaust on the market gives you this level of engineering, legal peace of mind, and riding experience combined. The investment gets you the best sound legally achievable on your motorcycle. Today, and as regulations continue to tighten. That's not a compromise. That's the ceiling, reached.
How to get the updated Smartbox software
Systems delivered from September 1, 2025 onwards come standard with the latest software. For earlier systems, ask your nearest authorized dealer about an exchange — they can advise you on options and pricing for your specific model.
If you're already happy with your current system, there's no urgency. But if you want to get the most out of The Exhaust, this is the upgrade to ask about.
Still not sure? Come and listen.
A lot of our authorized dealers have live demonstration systems. Before forming an opinion based on forum posts or hearsay, visit a dealer near you and hear a Euro 5+ system. That's the only way to truly judge it.