Quote:
Originally Posted by lsturbointeg
i'm trying to understand this mod. i know Bmw double you have something similar? so basically you tapped off your pipe close to the middle with smaller piping and than closed the end?  with Bmw doubles he has a removeable cap which makes sense but here it looks capped off? i only asked because once i slap those Meisterschaft's on i know it's going to be loud even tho it has EVC |
This is to cancel a specific frequency (drone frequency) and not tone down the entire exhaust sound. It is working like noise cancelling ear plugs but only effective for a short range of frequencies.
For example all frequencies from 40hz to 600hz where from 55 to 80 dB at 1800RPM except 100hz was 95db. So I calculated the length of the pipe to cancel 100hz sound and now the 100hz frequency has the around the same dB has the others.
Clearer now?
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BMW 535I xdrive 2011 M-Sport with H&R Springs, Niche Form Wheels 8.5 ET35 / 10.5 ET35, Continental DSW06 245/35 & 285/30, JB4 Map 5, ER Downpipe, Megan Racing Quad Exhaust with Vibrant resonators, M5 Diffuser, Orange reflector shaved and removed xdrive badge.