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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > Some exhaust info I just came across - Magnaflow related



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      06-15-2007, 02:52 PM   #1
S4to335
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Some exhaust info I just came across - Magnaflow related

This information was taken from a post by an ex-employee of Magnaflow..when he was responding to someones complaint about drone...

Remember this is not my comments..but those of someone else..dont direct questions about this information back to me please...thanks.

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Having worked at MagnaFlow for several years, I can tell you that nearly ALL aftermarket exhaust systems will produce some level of drone (really, resonance) at this low rpm.

On the RS4 with my MagnaFlow, the drone was extremely minor and was gone by 2200 rpms.

I don't want to come off as harsh, so please forgive me when I say this:

Normally I tell people that if A) they're lugging their car about town at this low of an rpm, they're not in the right gear and they're certainly not driving the car right way. There's very little power to be had at this low rpm in the RS4 and I rarely run mine below 2500 rpm and B)if you're not willing to accept the drone that again will come from ANY aftermarket system and the extreme low end of the rpm scale, then you are not a good candidate to be an owner of an aftermarket exhaust.

Typically, people who complain are much older, or have little experience with aftermarket mods/performance cars.

The MagnaFlow system features an X pipe, rather than an H-pipe style cross over pipe. Some systems have no cross over pipe at all.

The X pipe equalizes exhaust gas pulses from both banks of cylinders, which among other things reduces resonance. However, there will always be some resonance at the low end of the rpm scale. Getting rid of it may be possible, but not without sacrifice.

How do you get rid of it?

By installing resonators...which, even then, will only reduce by 25-50%. The trade off is that choking the system down with resonators also reduces the power gain from the system by about the same amount.

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