Help with exhaust drone

[cu260r6]

A few months ago I cut off my stock muffler and replaced it with a sport muffler. I wanted to experiment to see if it added any low-end torque for around town, and it did give a nice kick and seems to spool up quicker for the first 2k rpms. However, the drone is absolutely killing me! It only occurs between 2k and 2.5k rpms, and I'm wondering if anyone has any suggestions on moving the drone range lower or higher in the rpm range.

Initially, I tried it without a muffler, with just the resonator. There wasn't any drone at any particular rpm, but it was a bit too loud everywhere. I then added a really cheap muffler that is basically nothing more than a metal box the shape of a muffler with two metal barrier walls inside. There's no baffling or packing.

I'm considering going with the muffler shop's recommendation to just add another resonator, but I wanted to see if anyone has solved this particular problem. I'd obviously rather not pony up $500-700 for one of the normal aftermarket systems or a BMW PE, and I don't want to give up my nice, new-found torque gains.

[TheSt|G]

So to get this straight, you hacked off your factory muffler, mounted a generic unit, and then are curious as to why it doesn't work?

Also, despite the placebo you likely lost power. BMW exhaust components are pretty excellent from the factory.

[Dafttt]

Don't get cheap with the car. You already paid x-amount for it, what's another $500-$700 for a proper exhaust set up?

I'd honestly just hone in the sound. Lots of other ways to get torque from the engine without it sounding like a tractor.

[mechavore884]

the factory exhaust is around 2.5"s.....thats pretty badass compared to most vehicles these days. Im not 100% sure if this could be implemented but you might want to see if you could pack in more glass packs :\

[631twentyeighteye]

I noticed virtually no different going from a stock exhaust, to a performance exhaust, to a resonator and muffler delete. Other than the glorious exhaust note getting louder and louder. I have horrible drone and my car is obnoxiously loud, my friends can hear from inside their houses as im on the way to their houses.

However, i'd recommend getting a performance exhaust. It will do everything you're looking for.

[cu260r6]

I doubt there's any gain on a dyno (full throttle), but I think there was a nice gain at partial throttle at very low rpm. Plus, the stock behemoth weighs 50lbs. Why not get rid of it? But point well taken, I'll probably experiment with a variety of normal sport mufflers to replace my $10 cheapo temp fix.

[zoomnad]

Ear plugs work.

[andrey_gta]

adding a resonator that sits in the dones's sound frequency is the solution. I seen a thread on e90post that shows some calculations.


I do support whats been said here, get a new exhaust. Magnafow is quite cheap and you get a resonator + muffler

[mechavore884]

^ +8 ...on a side note isn't the magnaflow still around $700? and has anyone dyno'd one?

[TheSt|G]

Originally Posted by mechavore884

^ +8 ...on a side note isn't the magnaflow still around $700? and has anyone dyno'd one?

Apparently there are always discounts floating around for them. Not my choice but certainly better than some Pep Boys generic unit.

[mechavore884]

Just out of curiosity what would be your best recommendation? I've seen some just get a aftermarket 135i exhaust and "perform surgery" to get it to fit...IDK personally I would go with the better flow rates and larger piping

[TheSt|G]

Originally Posted by mechavore884

Just out of curiosity what would be your best recommendation? I've seen some just get a aftermarket 135i exhaust and "perform surgery" to get it to fit...IDK personally I would go with the better flow rates and larger piping

You aren't going to see any gains with muffler work, so do whatever sounds good to you/isn't going to fall apart.

Large diameter mid pipes can gain HP, but sacrifice all low end torque for it.

[mechavore884]

sounds like a bucket and duct tape is in order

[TheSt|G]

Perfect.