Exhaust modes, do they affect power output?

[ba15996X50]

I like my RR set in the quieter, exhaust modes. Any thoughts on restricting horsepower output. Particularly now that I’m about to get the Procal tune.

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[yelnoc2]

I run 95% Baha mode, love the sound. Quick google did not reveal any claims of increased HP in Baha. BUT that sort of flies in the face of less back pressure being bad for performance, and I think that means one must assume that Baha mode has less backpressure than Quiet. Borla claims significant HP gains with their catback systems. Here in an interesting article, but unless we had dyno tests of the various exhaust modes we are probably just speculating https://www.roadandtrack.com/new-ca...ackpressure-and-why-is-it-bad-for-horsepower/

 

[Catalyst]

I watched a video before I had my RR and I believe it was Fabulous Fabrications in Australia when they were trying to develop a full exhaust system. They showed the butterfly valve exposed in each mode after removing the section of pipe behind it. If you go WOT it opens fully regardless of mode. At idle and low loads the quiet mode they are shut, normal like 1/3 open, sport 2/3 open and baja full open (as if WOT) even at idle. There is also a back pressure relieving exhaust bypass from the muffler bypassing the valve that would allow exhaust to exit as needed if the valve was still mostly closed.

I suspect there is a little change in power at lower throttle input levels, but WOT should be full open in any mode.

 

[Catalyst]

Found it...

 

[Mgrmax]

I also wondered about this.

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