Have you noticed that your $837,000 McLaren Senna is a little ... different from the one belonging to your pal in Monaco? You're not crazy. It turns out, the Senna comes with one of two different exhaust systems, one with three tailpipes, one with only two. And it all comes down to where you'll be driving your trackday weapon.
This tidbit first came to our attention via . In it, he explains that the three-tailpipe arrangement is the "EU-compliant" exhaust system, while the two-pipe exhaust is for customers outside the European Union.
As Peloton25 explains, the three-pipe system is required in nations that apply the EU Type Approval automobile standards. This set of automotive regulations includes a rather stringent limit on exhaust noise. On EU-compliant Sennas, the exhaust flows through the bottom pipe in low-speed driving, routing through an additional muffler to hush the 789-hp twin-turbo V8 to a suitable level. At higher speeds, a baffle system in the exhaust re-routes flow to the upper two pipes, bypassing the muffler and letting the car sing its full-throated wail.
For nations that don't require EU-compliant exhaust, the Senna comes with a two-pipe system that does away with the third pipe and its associated muffler. As Peloton25 points out, the two-pipe system is simpler and lighter than the EU-compliant exhaust—no additional muffler and no active baffle system to mention.
McLaren explained the system at the announcement of the Senna:
The unique Inconel and titanium exhaust is another key element of the high-performance powertrain. Exiting through the ultra-low carbon fiber rear deck, the exhaust tips are angled so as not to disrupt airflow around the rear wing and rear diffuser. The exhaust, which is tightly packaged and engineered to reduce weight, uses either a twin-exit or triple-exit active system depending on market requirements. The latter is standard-fit in EU market, the exhaust system concept having been refined to reduce the exhaust valves from 4 to 2 and enable a customer to have a quieter mode at lower engine speeds and a more engaging exhaust note at higher engine speeds and loads on tracks.
And since you're wondering: Yes, that means the US gets the louder two-pipe system, as you can see on Michael Fux's Senna, the first delivered to North America:
So there you have it: Next time you see a Senna, check the exhaust system. It'll tell you whether the car was ordered for the European Union or the rest of the world. We have a feeling, no matter which system you come across, it'll sound just lovely.