Mazda Talk Forums

My 2008 NC PRHT is the best daily driver I have had.
My question revolves around the cabin noise. I have quite sensitive hearing, between the drone, road noise, etc it can be overwhelming when trying to listen to music. I have added some extensive sound deadening around the cabin, but I want to knock it down even more.

How much could the helmholtz midpipe knockdown the stock exhaust cabin noise?
I might consider the RoadsterSport street header as well... to help power offset the weight of sound deadening material

What exhaust system is on there now?

Completely stock exhaust, unless the factory sport suspension, LSD pkg changed the exhaust any.

Okay, any addition of header is going to raise sound over the highly restrictive stock system. The Helmholtz midpipe is highly effective on a narrow frequency range....it is designed to kill that 'drone' at steady state cruising. But when you accelerate to pass, enter the freeway, the helmholtz midpipe is going to be noticeably louder than stock. Thus, for you I cannot suggest aftermarket exhausts, all of them are going to raise the sound levels, not lower the sound.