Dyno test: Power Effects mufflers

[treynor]

While on the dyno this morning testing the my newly-installed Hennessey heads (separate thread) I also performed one non-NOS run with the Power Effects mufflers on full-quiet mode. In this mode, the main passage through the muffler is blocked by a butterfly valve, forcing the exhaust gases to route around the outside of the muffler. The result is lower flow, but also lower exhaust volume. The volume difference is quite substantial, and to date the question has been how much performance is sacrificed? The result, at least for a car (like mine) with catalytic converters, is "not much":

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[treynor]

Not a prayer of passing Laguna's sound test, quiet mode or no. Maybe with the Belanger headers... I'll do a dB test outside the car to provide some hard numbers, but subjectively the Viper's now louder than some aftermarket bike exhausts at full honk.

 

[Nadine UK GTS]

Mines registering 127DB at 4500rpm, this is loud! The DB rating equates to similar of an F1 car! I have 3" straight through and no cats.