Bedford noise limits in normal car, decibel reduction kits?

[px1980]

I'm debating buying a Cayman with a view to use it regularly on track (but also on road/as daily), either 718 GTS 4.0 or 981S.

Bedford is the venue that works best for me (by far the nearest & I'm new to TDs so big run off is a massive plus). I'm a little concerned having read about people getting black-flagged in their normal road cars due to drive-by noise limit violations. I called MSVT and they said factory Cayman "should be absolutely fine", but then people's reports on here suggest otherwise.

I'd like to avoid a situation in which I spent tens of thousands on a second car, then find out I can't use it at my preferred track.

In case it does happen to me, what are people's views on decibel reduction kits such as https://www.demon-tweeks.com/uk/decibel-slayer-bol... ? Basically, can I assume that in worst cay scenario on the day, I'd just slap this thing onto the exhaust and that'd be a sure-fire way of ensuring I can carry on with my trackday?

Or maybe this is a non-issue, and in a car such as Cayman, I'll have no issues if sports exhaust is kept off? I find it a little hard to believe that a factory 2020 car (say the 718 GTS) might be in breach of noise limits, but there you have it...

[untakenname]

I'm concerned about how much backpressure is generated by these devices and the effects on the rest of the exhaust system (CATs), apparently just angling the exhaust path downwards so it hits the tarmac and then reflects up lowers it by quite a bit.

Oddly enough my car complies with the noise limit at Bedford but have been black-flagged at Brands Hatch which has a higher limit, I think atmospheric conditions play a large part as well as the car.

[TTmonkey]

Go to a track day as an observer. Observe other cars. See which breaks the limits.

Act on your findings.


I’ve only seen these devices on TVRs on track days, but that was years ago.

[px1980]

TTmonkey said:

Go to a track day as an observer. Observe other cars. See which breaks the limits.

Act on your findings.


I’ve only seen these devices on TVRs on track days, but that was years ago.

Well I have been, I've definitely seen Nissan GT-Rs, AMG GT, 911s, Lotus Exige's. So plenty of cars which I'd assume (?) would be in the same noise bracket as a Boxster GTS. But whether you get black flagged or not at Bedford seems a little random...

[TTmonkey]

px1980 said:

TTmonkey said:

Go to a track day as an observer. Observe other cars. See which breaks the limits.

Act on your findings.


I’ve only seen these devices on TVRs on track days, but that was years ago.

Well I have been, I've definitely seen Nissan GT-Rs, AMG GT, 911s, Lotus Exige's. So plenty of cars which I'd assume (?) would be in the same noise bracket as a Boxster GTS. But whether you get black flagged or not at Bedford seems a little random...

Last time I went two GT3 RS’s were kicked out of the event because of noise and because they were there to race each other. They were told to stay apart but they were there to be together, and both going through the noise checks together, right pair of asholes.

I’ve never seen a booster/cayman black flagged.

[px1980]

TTmonkey said:

Last time I went two GT3 RS’s were kicked out of the event because of noise and because they were there to race each other. They were told to stay apart but they were there to be together, and both going through the noise checks together, right pair of asholes.

I’ve never seen a booster/cayman black flagged.

haha this is hillarious;) And thanks for clarifying re. boxster/cayman. You'd expect there to be a biiiig difference in noise levels between GT3 RS and non-GT Cayman (including 4.0 GTS, I'd hope)

[UTH]

px1980 said:

Well I have been, I've definitely seen Nissan GT-Rs, AMG GT, 911s, Lotus Exige's. So plenty of cars which I'd assume (?) would be in the same noise bracket as a Boxster GTS. But whether you get black flagged or not at Bedford seems a little random...

It's an interesting point on the random side of it. I've been to Bedford several times in my Evo VI, and never had an issue, always passed the static, and never black flagged. The last time I went (which was well over a year ago now) I passed static fine, but was black flagged twice on the drive by. Sadly I couldn't remember what I'd changed on the car in between the times I'd been (had a few issues with it over the years requiring a fair few changes, so there's a chance it was actually louder than the previous time) so I wasn't sure if I genuinely had become louder, or was I just randomly caught out on a 'bad day'.

Wind direction, atmosphere? Was I very close to the limit and on another day would have been fine?
It has put me off going again in case I had the same issue, although I have bought a bigger silenced decat which I'm going to fit and maybe give Bedford one more try.

[UTH]

px1980 said:

I'd like to avoid a situation in which I spent tens of thousands on a second car, then find out I can't use it at my preferred track.

I hear you here!! My Corvette is (beautifully) loud....I knew this going in, but I thought 'loud' days with 105 static, 101 drive by I'd be ok, but turns out I'm a little too loud even for the 101db drive by! So I won't ever be able to truly floor it around a track in the UK in it. Not the end of the world as I didn't buy it as a track car only, but it would have been nice to go to a few without worrying.

[brillomaster]

keep the cats in and the standard exhaust on and you'll be absolutely fine.

most really loud cars either have the cats removed or the back box removed, or both.

but with both in place i'd be surprised if you break 90db static, let alone 87db driveby.

[UTH]

brillomaster said:

keep the cats in and the standard exhaust on and you'll be absolutely fine.

most really loud cars either have the cats removed or the back box removed, or both.

but with both in place i'd be surprised if you break 90db static, let alone 87db driveby.

Standard exhaust long gone, sadly. I did buy a 'silent' system as well as silent decat to keep it as quiet as possible. Of course, as is usual with Evos, it's been mapped with a decat to get the most power out of it.

Never failed the static, just the driveby has been the issue. Which would suggest to me I can't be much higher than the 87db.

[px1980]

UTH said:

I hear you here!! My Corvette is (beautifully) loud....I knew this going in, but I thought 'loud' days with 105 static, 101 drive by I'd be ok, but turns out I'm a little too loud even for the 101db drive by! So I won't ever be able to truly floor it around a track in the UK in it. Not the end of the world as I didn't buy it as a track car only, but it would have been nice to go to a few without worrying.

What a shame. I did actually briefly think of getting the new 2020 UK-spec Corvette (C8) which seems rather good value-for-money, but I quickly realised it wouldn't be an option for track (due to noise & also weight)

[UTH]

px1980 said:

UTH said:

I hear you here!! My Corvette is (beautifully) loud....I knew this going in, but I thought 'loud' days with 105 static, 101 drive by I'd be ok, but turns out I'm a little too loud even for the 101db drive by! So I won't ever be able to truly floor it around a track in the UK in it. Not the end of the world as I didn't buy it as a track car only, but it would have been nice to go to a few without worrying.

What a shame. I did actually briefly think of getting the new 2020 UK-spec Corvette (C8) which seems rather good value-for-money, but I quickly realised it wouldn't be an option for track (due to noise & also weight)

Outside of the track limitation factor, from what I've read you would NOT regret getting a C8, so don't rule it out. Trips to Europe with some track days thrown in could well make it worthwhile......

[NardoRS]

You should be fine in your Cayman at Bedford. I’ve been there 3 times in my Audi TTRS and, even though I was well under the static, I did trip one of the track side meters. It was always the same one and I finally figured out it was a gear change happening in line with the mic; I had to short shift at that point and had no more problems.
I did test the static with exhaust valves open and was just under the limit.
I think you’ll be ok and my experience each time was the circuit staff want to help you comply.

[QBee]

As said, a damp misty morning can play havoc with the static test.
I failed one year, but when a Porsche GT3 failed straight after me, they re-instated both of us with dire warnings about the drive by.
I always have to short shift before the noise meter on the short straight.2/3rds of the way round.
I used to use bolt on cans on my TVR, but have now made a more permanent noise reduction change - I stuck a GT35 turbo on it, which knocks off 10 decibels.

[px1980]

NardoRS said:

You should be fine in your Cayman at Bedford. I’ve been there 3 times in my Audi TTRS and, even though I was well under the static, I did trip one of the track side meters. It was always the same one and I finally figured out it was a gear change happening in line with the mic; I had to short shift at that point and had no more problems.
I did test the static with exhaust valves open and was just under the limit.
I think you’ll be ok and my experience each time was the circuit staff want to help you comply.

thanks. The TTRS is quite a noisy car in general, right? I've never driven or probably even heard one, but reviews mention "sonorous";) So if you're "well under" on the static test, I hope that the Cayman will be, too (it'll be the 6-cylinder 4.0 without turbo though)

Edited by px1980 on Wednesday 6th January 09:40

[UTH]

px1980 said:

NardoRS said:

You should be fine in your Cayman at Bedford. I’ve been there 3 times in my Audi TTRS and, even though I was well under the static, I did trip one of the track side meters. It was always the same one and I finally figured out it was a gear change happening in line with the mic; I had to short shift at that point and had no more problems.
I did test the static with exhaust valves open and was just under the limit.
I think you’ll be ok and my experience each time was the circuit staff want to help you comply.

thanks. The TTRS is quite a noisy car in general, right? I've never driven or probably even heard one, but reviews mention "sonorous";) So if you're "well under" on the static test, I hope that the Cayman will be, too (it'll be the 6-cylinder 4.0 without turbo though)

Edited by px1980 on Wednesday 6th January 09:40

My only word of caution is that just because you may come in below the static, it seems you could still be caught out on the drive by like I have been.
Short shifting etc can be done when passing the mics, just bear in mind the static test isn't a perfect indicator of being fine out on track.

[px1980]

UTH said:

My only word of caution is that just because you may come in below the static, it seems you could still be caught out on the drive by like I have been.
Short shifting etc can be done when passing the mics, just bear in mind the static test isn't a perfect indicator of being fine out on track.

Thanks, and agreed, it does seem that 90% of people who report problems at Bedford are caught out on the drive-by, not static.

Hence me asking in the original post about those exhaust decibel reduction kits - i.e. can I assume that should I be unlucky (because it does seem to come down to luck) on the drive-by, there is "something" that I could buy, have in the boot of the car at all times and just slap/screw on the exhaust after say the second black flag, when I'm running a real risk of being thrown out.

[UTH]

px1980 said:

UTH said:

My only word of caution is that just because you may come in below the static, it seems you could still be caught out on the drive by like I have been.
Short shifting etc can be done when passing the mics, just bear in mind the static test isn't a perfect indicator of being fine out on track.

Thanks, and agreed, it does seem that 90% of people who report problems at Bedford are caught out on the drive-by, not static.

Hence me asking in the original post about those exhaust decibel reduction kits - i.e. can I assume that should I be unlucky (because it does seem to come down to luck) on the drive-by, there is "something" that I could buy, have in the boot of the car at all times and just slap/screw on the exhaust after say the second black flag, when I'm running a real risk of being thrown out.

Yeah it's certainly worth having one, even if it's just to show the marshals that you have something you can fit in an attempt to reduce your noise so you can be let back on. Even if you don't fit it and then just short shift, it'll buy you another chance if they're being extra vigilant rather than just saying "nope, nothing I can do".

[blue al]

Also watch out for lifting off near mikes as dependent on maps/fuelling that can also induce pops and bangs at the wrong time and place

[Dan_The_Man]

Been black flagged there several times and it's always on the drive by, car is a Honda Civic Type R. It was very strange as we run with an extra exhaust box sticking out of the car and it turned out the supercharger induction noise was triggering it so a new re-designed baffled intake has meant more Bedford track time.