Originally Posted by FastAndFurious
I'm wondering if the quad exhaust system is similar to that of the Alfa Romeo Giulia where an electrically adjustable exhaust system controls the exhaust valves depending on the selected drive mode. So the valves for the two inner exhaust pipes are closed while in quiet mode and all four may be opened up in the other drive modes.
They do, and it's something i'm surprised that no review has shown and i've seen just about every NSX review out there by now. Here's the breakdown, explained by Acura:
Integrated Dynamics System (IDS)
The NSX Integrated Dynamics System (IDS) provides the driver with four selectable dynamic modes—Quiet, Sport, Sport+ and Track. The system integrates all of the vehicle's dynamic chassis and powertrain systems—steering, brakes (mechanical and electro-servo), throttle, vehicle stability assist, magnetorheological dampers, engine, transmission, and Sport Hybrid SH-AWD control systems.
From the available all-electric operation of Quiet mode to the closed circuit, maximum performance capacities of Track mode, IDS progressively dials up the dynamic characteristics of the vehicle based on the needs of the driver and the driving environment.
In addition to these dynamic system variations, IDS varies cabin sounds via Active Exhaust Valve (AEV) and new Intake Sound Control (ISC). ISC uses twin pipes with an electrically controlled valve to vary the sound being transmitted from engine air intake system to twin outlets in the rear uppermost portions of the cabin. Utilizing these technologies, IDS is able to fine-tune cabin sound quality and volume to match the dynamic character of the vehicle in Quiet, Sport, Sport+ and Track modes. Of note, there is a full 25 dB volumetric sound difference between Quiet and Track modes—a tremendous variance in audible sensation.
Quiet mode prioritizes electric-only driving at lower speeds, maximizing energy efficiency and minimizing cabin sound. The vehicle uses the TMU for initial launch from a standstill. When power demand requires the engine, it starts more quietly than in other modes and maximum engine speed is limited to 4,000 rpm, while the Active Exhaust and Intake Sound Control valves are closed for a more hushed operation. The transmission shift map also prioritizes lower engine speeds. The Driver Interface (tachometer and center console information display screen) features a cool and quiet blue color.
Sport mode takes advantage of the Sport Hybrid system to offer the driver a direct responsive vehicle or a more relaxed vehicle according to their driving inputs. Compared to Quiet Mode, it eliminates the 4,000 rpm limit on the engine and provides a more aggressive throttle map for quicker response. A more aggressive transmission shift map holds gears longer and allows higher rpm shift points. The Intake Sound Control system and the Active Exhaust Valve are activated, allowing exhaust and intake sound to permeate the cabin for a more emotional driving experience. Like the Quiet mode, sport mode provides idle stop function. The Sport setting is the default setting in normal vehicle operation.
Sport+ prioritizes maximum drivetrain response and dynamic performance with faster up- and down-shifts of the 9 DCT and still more aggressive throttle mapping. Maximum use of the electric motor torque provides more explosive acceleration. Increased agility is achieved by harmonizing a more aggressive Direct Yaw Control setting that works in concert with the magnetorheological dampers, Agile Handling Assist, and the Electric Power Steering System—perfect for a spirited drive on a winding road. It also offers the driver a higher degree of steering feedback, while intake and exhaust note sounds via Active Sound Control are further increased for an even more exhilarating and emotional driving experience. The TFT Meter sports an aggressive yellow "con-trail" along the tachometer needle supporting easy recognition of engine RPM. Red highlights for the center console information display also reinforce that the driver is in now in Sport+ mode.