550 Maranello rear exhaust marked with ”550”

Yes, you have tubi rear mufflers installed. The first generation tubis will have no embossing on them. A few late mufflers are embossed 550. These had resonance issues corrected.

The second generation tubis are embossed 575. I have straight center pipes and second generation eubi mufflers on my car and there is no resonance...


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I'm happy with the sound. With straight pipes replacing the center resonator, you hear each engine bank separately with a nice burble at idle and a rich 12-cylinder sound when you get on the gas.

Here's how my car sounds with wide open throttle coming down the front straight at Daytona International Speedway...




4:50 6:16 7:58 and 9:48


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Yes, get some some straight pipes to replace your center resonator. Your exhaust note will come alive. A good muffler shop can fabricate them easily for you.

No, it won't sound like a Formula 1 car of yesteryear, but it will sound like a 12-cylinder GT car.

 

As your tubis have no valves, with this setup, you'll lose functionality of the Variable Length Intake Manifold which is evident on a stock 550 dynograph but replacing the restrictive center resonator makes up for it.

 

You can use your original headers and catalytic converters as I did.

 

Why? The rod that controls the 12 throttle bodies in the center plenum is vacuumed-powered through ECU triggering and whether the mufflers are valved or not will thus not affect the intake modes.
I also don't understand the logic in the document you posted, as the dyno runs may have been done in full load and as explained in the document the short path will always be on with the throttle at 100%.

What is important when fitting unvalved mufflers is to plug the vacuum source to the (deleted) valves, at the outlet of the solenoid at the back.

 

Barry- Affirmative, the straight center pipes have nothing to do with the dual length intake manifold. All late 575Ms have straight center pipes and those have no effect on the intake manifold.

 

Thank-you Timmo and Terry. I stand corrected.

 

No, no drone at low RPM with my setup.