Resonators - leave them or remove them

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Oct 13, 2006 | 03:18 PM

#11

jet190rs

Senior Members

Joined: Sep 2004

Posts: 2,074

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From: New York, NY

My Ride: '05 545i - scheduled for ED pickup in Munich on 7/22!

Quote:

Originally Posted by jsal' post='344598

Also, do you think you really lost low end torque, or is it just a perception from the exhaust being louder? I would not think there is much backpressure change. The resonators are basically straight through pipes with packing around the outside of a perferated pipe. I guess there is a smoother flow of the exhaust.

that's what i thought resonators were, but on the first day it def felt slower at low revs so i became fairly certain that i lost back pressure. however, i drove a good amount today and it felt much better. it almost felt the same as before i removed the resonators, so maybe it just took the ecu some time to readjust...???

Oct 13, 2006 | 06:28 PM

#12

gasterus

Senior Members

Joined: Oct 2005

Posts: 298

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From: Indonesia

My Ride: 645Ci black/red, Eibach springs, K&N air filter, Wetterauer ECU upgrade, Eisenmann 83mmx4 exhaust, 20" Sportec wheels-Michelin PS2 tires, Hamann front add-on lip

Quote:

Originally Posted by jsal' post='344192' date='Oct 12 2006, 10:24 AM

I know we addressed this topic last year, but I started thinking about it again.

Last weekend I pulled into the gas station next to an M5. Great guy who is also a forum member. He said he removed his resonator and got a little more growl from the car when he got on it and it was not overly obnoxious or noticable on the freeway.

I know the V-10 probably has very different harmonics and they seem quieter than a V-8 at times.

I like my Hamann quad exhaust. Although I would not mind a little extra sound when I jumped on it. I just don't want to have an obnoxious resonance vibration when cruising down the freeway or when the engine lugs in 6th gear.

So, should I:

- Leave it
- Remove the (2) single resonators behind the cats
- Remove the box resonator in the back
- Remove all

It would be really nice to test it without costing an arm and a leg if I did not like it.

Any feedback from someone who has done it would be much appreciated.

I bypassed all the resonator on my 645, but I would guess it would probably has the same effect on the 545i.

1.Remove the box resonator in the back. (almost no difference in sound volume, definitely no sound difference from the cabin.

2. Decided to remoce the resonator behind the cats. (more throaty and definitely more aggressive sounding, and no resonance in the cabin

But you could feel very slight vibration in the cabin during idling)

I also change my muffler to the eisenmann. Here's the vid clip!

http://video.google.com/videoplay?docid=-6...amp;q=bmw+645ci

Oct 22, 2006 | 10:40 PM

#13

jet190rs

Senior Members

Joined: Sep 2004

Posts: 2,074

Likes: 0

From: New York, NY

My Ride: '05 545i - scheduled for ED pickup in Munich on 7/22!

Update (slightly off topic):

recently also deleted charcoal filter and replaced stock air filter with k&n air filter.

the remus/straight pipe/k&n/de-charcoal combo now ROARS between 2k-3k rpm!
also, the filter combo makes the car pull harder, so it seems the performance loss from the straight pipes alone has been offset. the car now pulls about as fast as before all the changes.

however, i don't know if i can cruise at 80mph (~3k rpm) for a long time because the filters put the amount resonance over the top. 60mph (~2k rpm) is fine though.

i wish i had a camcorder to film some video clips for you LOL...i get so many stares in nyc when i take off or downshift!