decibel reducers

[Freddie44]

Yep I've got the standard black tips and had RPM fabricate to fit
Had to wait around a month to get them back

[Paul_M3]

I've got a couple of quiet track days coming up, and I was worried about failing the drive by tests.

(I've got a very restrictive but effective contraption for getting through the static tests)

After a bit of research I thought the Decibel Devils seemed like a decent option, but was concerned they wouldn't quite be effective enough.

I'd also read about some of the 911 race cars having down-turned tailpipes to reduce noise.

So my obvious thought was why not combine the two? 2 Decibel Devils were ordered, along with a couple of 90° exhaust bends.

A bit of welding later, and...



I have no idea how much difference the down-turns will make, but they can only help.

I'll give the whole lot a coat of high temperature black paint to neaten it up a bit, and then see what happens at Rockingham next Friday.

[ttdan]

Just depends where the noise numpty points his mic! Good luck :-)

For 105db static days i have used these (without the down turn bit) on an X pipe amd made it through OK.

[adbett]

this is great thread! my 996.2 GT3 has the standard exhaust and end tips and is about 104-105dB static, frustrating as it limits the tracks and events you can do

I'm thinking it would be easier to modify the ACT reducers to fit the exhaust with the oval tips removed rather than try to fit it over the top?

[SignalGruen]

adbett said:

this is great thread! my 996.2 GT3 has the standard exhaust and end tips and is about 104-105dB static, frustrating as it limits the tracks and events you can do

I'm thinking it would be easier to modify the ACT reducers to fit the exhaust with the oval tips removed rather than try to fit it over the top?

I'm thinking about buying some tail pipes and cutting off the oval pipes and having circular tips welded on so that I can fit the ACT - not sure if this is feasible as I haven't yet looked at the tips closely. That said, my standard 996.1 GT3 passed the 101Db static noise test for the Brands Hatch GP event the other day but I get the feeling it was marginal.

[CocoPops]

Paul_M3 said:

I've got a couple of quiet track days coming up, and I was worried about failing the drive by tests.

(I've got a very restrictive but effective contraption for getting through the static tests)

After a bit of research I thought the Decibel Devils seemed like a decent option, but was concerned they wouldn't quite be effective enough.

I'd also read about some of the 911 race cars having down-turned tailpipes to reduce noise.

So my obvious thought was why not combine the two? 2 Decibel Devils were ordered, along with a couple of 90° exhaust bends.

A bit of welding later, and...



I have no idea how much difference the down-turns will make, but they can only help.

I'll give the whole lot a coat of high temperature black paint to neaten it up a bit, and then see what happens at Rockingham next Friday.

Hi,
How did you get on with this solution?
Considering the same idea for my car. Would be good to lose 2-3 dB on driveby.

[Paul_M3]

CocoPops said:

Paul_M3 said:

I've got a couple of quiet track days coming up, and I was worried about failing the drive by tests.

(I've got a very restrictive but effective contraption for getting through the static tests)

After a bit of research I thought the Decibel Devils seemed like a decent option, but was concerned they wouldn't quite be effective enough.

I'd also read about some of the 911 race cars having down-turned tailpipes to reduce noise.

So my obvious thought was why not combine the two? 2 Decibel Devils were ordered, along with a couple of 90° exhaust bends.

A bit of welding later, and...



I have no idea how much difference the down-turns will make, but they can only help.

I'll give the whole lot a coat of high temperature black paint to neaten it up a bit, and then see what happens at Rockingham next Friday.

Hi,
How did you get on with this solution?
Considering the same idea for my car. Would be good to lose 2-3 dB on driveby.

It worked very well, and I was happy.

Unfortunately I haven't got any definitive numbers in terms of decibel reduction as I didn't get before and after values at any circuits using the calibrated meters.

I did download the best reviewed iPhone decibel app which showed a few dB reduction. It was also noticeably quieter with the reducers fitted.

The added benefit if you're worried about drive-by noise is that you can angle the outlets straight down, OR to either side of the car. i.e. pointed away from a meter that mayt be causing you issues.