Magnaflows are really laud mufflers. Dynomax and Borla Turbos run less noisy. If you want to change, you may get your noise under control, but there goes more money....

Matt

 

I think if the noise becomes intolerable, a cheaper option might be to add another resonator right before the muffler. I don't know though. I'll try to get used to it, but if I can't I may have to start exploring these options. Any other cheap ideas to reduce the noise on engine braking and WOT?

 

I agree in regards to magnaflows and sound levels. My custom 3" set up deleted the 2nd cat. I am currently running on the stock dp and cat with no resonator and is a bit loud, so I can imagine your set up would be louder. i am looking to add a resonator somewhere in there to eliminate the drone i have on the highway.

here's a clip of mine:
http://www.youtube.com/watch?v=572ZL3XfF-I

 

my custom dynomax set up drones a lil on the highway. but i still have the second cat on. its 3'' all the way back. i can live with it. i might put in a resonator later on but the downpipe has to come on first. so i feel ya lxjose.

 

summit has a 3'' bullet muffler for about $40.00 im thinking it will do the trick for me. i think its about a 18'' one.

 

I 100% disagree that magnaflow are loud mufflers. You need some kind of muffler in the center of the car, not at the end of the exhaust. Be it a cat, resonator, or a muffler, the central muffler position eliminates drone. Don't know if theres any theory to it, but my experience tells it. My buddy has a 2.0t gti with a 3" turboback (no cat) just a magnaflow muffler in the middle. It sounds great, no drone whatsoever. My TT 225 has a 3" turboback with a cat and a magnaflow resonator in the center, its loud, but it doesn't drone at all. Of course, your mileage may vary. Slap a cat on that turboback and call it a day, it'll quiet down a lot. Another option is a magnaflow resonator (they flow well and quiet it down) Put as long of one as you can fit. If anyone has any specific questions you can pm me, I've been down this road many times. And now in welding school so I can offer exhausts that are unconventional and work.

 

Those of you with custom catback exhausts, can you tell if there's an increase in power? And which is the best muffler if one was to go the custom catback route?

 

Small update: CEL went off yesterday morning. Hasn't come back on since...will keep you posted.

Also, I was reading about how to eliminate drone and it says the best way is to shorten the amount of piping, which raised the rpm that the drone will occur at...how the **** are you supposed to do that without having a side-exit exhaust!?

 

like a pipe organ pipe or a flute (or a guitar string). It's usually the lowest frequency that can be sustained by the system (as opposed to overtones, or higher order pitches that can be sustained). To fight this, place a ressonator in the exhaust system. But if it's not the lowest frequency, then where you place the ressonator, and how much it affects the gas flow, will affect how much it changes the ressonance. So, to try to get lucky, don't place the ressonator exactly half way between the collector and the muffler, place it about 35% downstream of the collector or so. Also, get a ressonator that does more than just put a piece of pipe with holes wrapped with fiberglas and an shell. The more you perterb the gas flow, the more it will move the ressonance.

Now, this all goes back to partial differential equations, so if you want to go deeper, dust off the textbooks and read about string vibrations, pressure waves and the like.

If you want to experimentally determine where to put the ressonator, you can see where the vibrations in the pipe are largest (this is the viibrational anti-node, or place of maximum amplitude) and put the ressonator there. You'd need to use some sort of accelerometer to find it. Maybe a microphone that you place near the pipe, and move it to see where the laudest point is.

Good luck,

Matt

 

This explains why my exhausts have always come out great with the muffler more towards the center! Thanks for the explanation!

I'm partial to magnaflow mufflers, extremely free flowing and straight through. Do NOT get mufflers like flowmasters, chambered mufflers suck, provide too much flow resistance.

I still totally disagree that they're loud... But borlas are also straight through and in my experience about as loud as magnaflow, no huge difference. Either way, they both sound great!

 

Okay, so I reached that point I knew I would...the system is too loud. I just got back from a 30 minute drive and my ears literally hurt so badly (and I wasn't even driving that hard). The drone must go! What are everyone's recommendations (part and brand) for a CHEAP fix for this, because I've already spent more money than I wanted to? And yes Dr Obnxs, a cat is an option I will consider, it just needs to be cheap and high-flow. Also, what are everyone's thoughts on placement of the cat? Does it still need to be in the downpipe, or would it be just as efficient at sound/pollution reducing later downstream in the exhaust system?

 

what is the composition of your turbo-back? the best composition is to have a resonator right after the cat and possibly one right after that.

 

for the cat. Don't go a cheap magnaflow cat, on the R53 it got cooked fast. Make sure you get a good metallic high flow cat that can take the heat.

It's shocking how your path mimicked mine. And despite what was posted in the thread, the Magnaflow is a very loud muffler. At least I think so....

Check out other's ressonators, I used a Magnaflow and it didn't quiet things down enough. FWIW, one of the early R53 guys did a 2.5" straight exhaust with a Borla Turbo and it worked out well for him.

Matt

 

2.5" 304SS, no cats at all, Vibrant high-flow resonator about 2 feet after the flexpipe, Magnaflow muffler.

Good God, man! Those Random Technology cats are expensive as hell! Any other recommendations for a <$100 cat that won't fall apart, as you say the Magnaflow will?

 

unlikely. cats are expensive.

 

A new proposition: probably going to add another resonator, except this one has little "cups" on the inner chamber that lead to the packing rather than the perforated core of my high-flow Vibrant resonator. Does that make sense? I'm not sure if there's a certain name for that type, but I was told it will reduce the sound a lot more than the other, but might result in a loss of a few hp. This resonator plus labor/install will only cost $50-60. What do you guys think of this idea?


PS: we should probably just change the name of this thread to "Zach's exhaust trial and error". Thanks for everyone's help so far.

 

Knowing Jan personally, and having spent well over 10k on almost every product he makes for our cars, I can assure you that anything he comes out with for the R56 or anything else will blow anyone elses product out of the water.

 

Okay, last question before I get this done. I drew up a little schematic of my exhaust as it is now to help orient everyone.



I'm going to be adding the resonator I mentioned two posts above, that has tiny cup-like projection sticking out into the lumen in order to catch some of the exhaust flow (as opposed to the one I already have that simply has a perforated inner chamber). A reminder about my current problem: I have a lot of drone on any engine braking above 2000rpm and on WOT above 3500rpm. My questions are:

1. Do you think I should place the new resonator at point A or point B on the above picture in order to solve my noise issues?

2. Do you think this will help with the engine braking drone, or only the WOT drone? I ask because I wonder if the engine braking drone is a byproduct of backpressure and that the cups wouldn't help this (I'm not an engineer so this may be waaaaay off).

Thanks again, and hopefully the next time I post I will have good news for you.

 

I think you'll have better effect there, but really, it's just a guess.

Matt

 

My call would be to run a larger volume [capacity] center resonator. The larger it is the more it's going to acoustically decouple the two sections of exhaust. What physical size is the current center muffler?

Nice little drawing! It's format very much resembles the exhaust I have for my R53, the main difference is that instead of the downpipe I have a tri-y header, and between the flex bellows and center muffler I have a Dynatech catalytic converter. The cat alone will quiet the system down substaintially, especially nearby the center muffler. It's a big reason why the stock R56 exhaust is so silent!

 

I don't recall the exact size but it's a Vibrant high-flow resonator an it's probably about 12-16" long and around 3.5" diameter. I think you're probably right on the larger diameter muffler but I already had the shop order the above mentioned one. So now I'm pretty much just wondering where to put it.

Thanks for the input guys.

 

Got the resonator put in. It actually is a bit quieter, but still nowhere near stock, obviously. But for $60, I'm happy with the reduction in noise. It didn't make a damn bit of difference on the engine braking noise, but the low-rpm drone is gone. I had to put it in the back because the resonator was a lot longer than I expected.





My only worry now is that my exhaust is getting pretty close to the ground, so if I lower it I may have to be very careful. There's about 6 inches between ground and lowest point.

 

Glad to hear it's better. My custom TBE for my R56 was mega loud on engine braking too; not sure why the R56 is so loud on engine braking, especially considering it shuts the fuel off!

6 inches of clearance; that's Mt. Everest compared to my 1.4" airdam clearance on my R53!

 

Yeah, the crazy thing is if I'm engine braking at like 2500rpm, I can give the slightest tap on the gas it becomes about twice as quiet!

Okay, maybe I should stop complaining about my clearance issues...I think I'm just looking for something new to b*tch about since my exhaust issues are over.

 

LOL!

I wish I knew why the system gets so loud upon fuel cutoff. I can't seem to wrap my brain around it. No combustion + just air pump + closed throttle body = mega loud? For what it's worth, when I recently drove a totally stock R56, it had a basically silent exhaust except for fuel-cut engine braking, I could actually hear a little bit of drone.