Miltek 'boom'

[simonpa]

Hi all,
sorry if this has been done to death in the past - I had a quick search and didn't find a definite answer..

I've just joined after buying an '03 S4 Avant. It was fitted with a Miltek cat-back (I think) system.

Whilst it sounds great under power, it is really boomy (sp?) between 1-2k, which covers most of my town driving.
SWMBO is not particularly impressed with this...

Is there a way to reduce/remove the boom without losing the glorious howl under power?

TIA - Simon

[xyber]

What gearbox?

[simonpa]

Sorry -manual gearbox.
Standard avant.

I have the original receipt from AMD in Essex, for:

Front link pipe
Left end right centre sections - non-res
Left and right rear silencer
Brace bar
Trims

Thanks!

[xyber]

The problem is any performance exhaust will have done kind of undesirable noise. I've got a theory that more gas/pressure passing through it, quietens the boom down abit because the outward force stabilises any vibration in the tube like a damping effect, like when you blow across the top if a bottle, the fuller it is, the less noise you get. I've got a full non-res milltek with downpipes and berely notice any booming, so there may be something in it.

So, what would SWMBO say about a grand spent in downpipes haha

[1781cc]

I get boom in mine but I got no cats or precats with racing downpipes so I expect it. but, I grew to love the sound, especially the popping when its cold.

[xyber]

My theory just failed right there haha

Unless yours is the engine noise not being dampened by any cats?

[SSS]

I've just changed to a non-resonated Milltek from a resonated milltek and get exactly the same drone at those revs, worst at 1600-2k. When the other half is in the car and I have to drive a little more sensibly I can minimise it by waiting until 3k to change up or if driving fairly slow putting it in 6th and cruising with revs just over 1k. If I'm in the 1500-2k band and need to accelerate i change down. With the radio on you can hide it - not ideal but when you are in the car on your own the noise is amazing

[gottanS]

Do you get the droning only with non-resonated or is it both types that drone?

The droning problem is what is putting me off getting a Milltek or equivalent..

[1781cc]

my missus just shakes her head so I purposely keep it higher in the rev range for her pleasure! lol

funnily enough, I think you get used to the sound, it doesnt grate me at all. in fact I think mine sounds more like a deeper voiced SUbura Boxer style engine.

[SSS]

Do you get the droning only with non-resonated or is it both types that drone?

The droning problem is what is putting me off getting a Milltek or equivalent..

I didn't notice any drone at all with the resonated milltek catback, it still sounds good when you are trying hard, just not as good as the non res.

It's definitely true about getting used to the noise

[simonpa]

I don't suppose there is anyone near North Hampshire with a resonated setup I can listen to?

Just changing the centre pipes may be the compromise I need

Cheers - Simon

[BillTheButcher]

I've got a non-resonated Milltek on my B6 S4 and it's very bassy from idle up to about 2k but I wouldn't say it boomed. Then again I had a very noisy Mk4 R32 before this...

[Digger]

I know this will seem like a daft question but roughly how much louder (listening from outside the car) would you guys say the NonRes is compared with the Res? Is it marginal, significant, or much louder?

At the moment I'd be looking at fitting a Res to an RS6 C5 to avoid any annoying drone. Only asking as I doubt I will ever get to hear both together and dont want to waste money on the wrong choice!

[BigAustin]

I had non-res setup on my auto.
It was that awful, it only stayed on for 10miles.

at around 1600-1800rpm, it droned really badly.

My exhaust making friend said it was to do with the stainless steel.
It resonates at a different frequency to normal steel.

[johnp68]

I don't suppose there is anyone near North Hampshire with a resonated setup I can listen to?

Just changing the centre pipes may be the compromise I need

Cheers - Simon

I've got a resonated Miltek on my B6 S4, no drone as far as I can tell. Work in Wokingham, is that too far from North Hampshire?