28 replies to this topic

[FLD]

Does anyone know how effective the tullet decat silencer is? I'm peed off with noise and this has been offered as an option. I'm supplying them a cat to replace the failed one (out of warrantee with only 1145 miles on it ) and I can get a decat silencer as well for 300 quid. I really need to know if this is any good.

[Hark]

Speak to Phear. Think he has one.

[Phear]

I can't say for certain because I fitted mine at the same time as re-stuffing my back-box (all the stuffing inside had turned into one big solid lump of glass). However the combination of the two brough the noise down noticably.

[techieboy]

Yep, I've got the first one they made after complaining about noise since day one and it did make a noticeable difference at the time of fitting. Can't remember what the back to back testing showed but think it dropped the output by 3dB. Not sure whether I've just grown accustomed to the noise or whether it's no longer effective but system as a whole is still too loud.

[FLD]

3dB isn't much Not for an extra 300 quid.

[techieboy]

Just dug back through some of the emails back and forth to Andy Tullet at the time I fitted the decat silencer.

Fitted the new silencer section in it's place on Saturday, for a trackday at Snetterton yesterday. I have to say, I was a little sceptical about how it could possibly make the system quieter, it looked more like it would actually make it louder. After fitting, it did sound a little quieter whilst idling on the driveway and I took it out for a drive and it felt like it might be a little quieter on the road. The static test yesterday was 96.2dB at 5200rpm, as opposed to 104/105dB at 4500rpm at Cadwell last time out. Will be interesting to see if that same low reading is repeated next month at Cadwell but I'd call that a success. I don't think it will get me on track at Bedford (or least keep me on track once I'm there) but I can live without that.

So it was a fair bit more than 3dB but, with the proviso that static noise measurement seems to be a fairly random thing, in my experience and seems pretty much unrepeatable. YMMV.

[smiley]

If only he would do some R&D into creating a 2.5" 93db system.

[Phear]

I wouldn't have said it was 8db quieter, mine probably dropped by 5-6db's in total.

[FLD]

OK, thanks guys.

[techieboy]

I wouldn't have said it was 8db quieter, mine probably dropped by 5-6db's in total.

No, I don't think so either. But static testing is totally random in my experience (as is drive-by testing) and is affected by too many external factors to trust any single reading. I'd get 10 different readings on the same day at the same place, hence the YMMV.

[techieboy]

If only he would do some R&D into creating a 2.5" 93db system.

But, how? What works on one car and one engine may have no resemblance to how it performs on another car.

[smiley]

Starting with a stage II SC would cover 80% of the people in trouble i would say.

[techieboy]

Why an arbitrary number like 93dB? What does than mean? Why not 95dB, 88dB or even 77dB? Is it static measurement? If so, at what rpm and distance? What sort of surface should the car be on? How far away should the nearest buildings be? Should the engine and exhaust be hot or cold? What should the weather conditions be? Is it drive-by? If so, measured at what distance? Measured at what rpm? What effect does the driver have? Measured with the wind blowing in what direction? What temperature does the day need to be? Wet weather or dry? How do you discount engine noise? How do you discount varying induction setups? What about tyre noise or other traffic? How would you feel if it measured 93dB on day 1 and was louder by day 7 - will he have fulfilled the promise of a 93dB system at the factory gate? So how long should it be able to meet whatever arbitrary number we put on it? Obviously, forever would be good but that's impossible. So maybe how many miles driven? But, what effect would normal driving have as opposed to constant track use, have on longevity? How does the mixture of your particular car affect temperatures in the exhaust and lifespan of the stuffing/cat? If you're burning oil, does that have any impact? It's not at all straightforward. The only thing you can do is to give him/someone your car and they build something to suit your particular car as I can't see how anyone can guarantee universally meeting noise limits.

[FLD]

This is my main gripe. The website claims "meets track noise limits". IMO that should mean that it actually meets track noise limits and the supplier should make sure it does just that. This usually means a good safety margin / tollerance. This was the reason I bought mine and with the noise issue, the cat failing after 1145 miles and theplated mild steel flexi piece I'm feeling a bit sore about it. Noise readings should be done at operating conditions which would mean warm engine, usually 3/4 max rpm, 45 degree angle from tailpipe and 50cm range. The meter should be calibrated (obviously). The variables will be air density etc and proximity of any buildings (50m to the nearest trees at my test site).

[techieboy]

I know, I know. The fact is the system does meet some track noise limits, just not all tracks (even then most of those tracks have quiet days and noisier days where you'd pass). It doesn't say it will meet every present noise limit or future limits. So where do you draw the line? I'm certainly not trying to defend the system, I've been hurt more than most financially when it comes to exhausts and have been kicked off once, have been warned at two other tracks and don't go anywhere near three tracks. Add to that I absolutely hate the tone of the "wall of noise" this system produces (a 2hr drive yesterday reminded me - apart from 20 seconds underneath bridges). But, I've never failed a static test anywhere (with any of the 6 or 7 exhaust systems I've had), it's drive-by that is the real problem where tracks (and where comfort) are concerned and there is no consistent method behind those measurements.

Static tests are just a stupid measurement and even when applied consistently they consistently produce inconsistent results.

I've been tested three times on one day and had different readings each time. On any given day, you could line up six ostensibly identical VX's with the same system on and I'd bet that each of them would give a different reading. Without creating a system that's no louder than an OEM system, how can a manufacturer legislate for those differences between cars and testing variances? What works on one car may or may not work on another car.

Look at Bedford. Infamously tight noise limits but the static test is 101dB that just about anything with an exhaust can pass. But, mega strict 88dB drive-by limit which, certainly in our case, is an absolute nightmare and the reason why evo generally only ever get one lap out of whatever exotica they put around the track there. If I'd bought the exhaust 3 years 6 months ago and I could get on at Bedford with it but, then the local council enforces tighter limits 3 months down the line that means the exhaust is no longer suitable, does that leave me with a claim against the supplier as it's no longer track friendly? How does this work one - one Thursday I take the car there to be tested for static and drive-by limits. The head instructor rags it around an empty track and radios back to the control room for the readings and I'm miles inside both. Six days later I go there for a trackday (with the car having done 16 miles back to the house and back to the track) and on my second lap I'm hauled in and told I'm 0.1dB under the drive-by limit and if I'm planning on staying, I'll have to lift past three of the four monitors.

What about Donington? When the Tullet exhaust was first designed and manufactured, Donington was a bankrupt building site with trenches across the track. Now it's re-opened and has a 98dB drive-by limit (measured in a totally different way to Bedford, I might add), was it down to Tullet to foresee that at the time they made the exhaust and design the system to fit within a limit that didn't exist and does the fact it might not meet those limits now mean it's not fit for purpose?

Maybe buy a 2Bular system if you can handle the possible infinite wait but it would appear that they're not all created equal either.

Like I said, I'm playing devils advocate here. I hate the system and the noise it produces. I'd love it if it made no more than a whisper. But, it doesn't and I'm resigned to that fact and that it'll be me that has to find a workable solution for my car if things are to improve.

[iVXT]

How come the cats out of warranty? Do they not give a lifetime warranty with system for the first owner anymore or is it a cat get out claws?!? (Sorry couldn't resist) I thought db was measured at 1m from tailpipe at the 45 degree angle as you said though?

Edited by iVXT, 28 June 2012 - 03:06 PM.

[smiley]

Why an arbitrary number like 93dB? What does than mean? Why not 95dB, 88dB or even 77dB?

93 on driveby was just sucked out of my thumb. less is better.
95 on driveby seems to be the most common bottom at tracks these days.
I have the same frustration as you that the most expensive part i ever bought for the speedster, sold as meeting track noise limits just does not cut it, and i am fiddeling with different back boxes, and db killer crap and whatever.

Just very disapointed with mr tullet atm.

[techieboy]

I thought db was measured at 1m from tailpipe at the 45 degree angle as you said though?

That's what the MSA say. But environmental and operator factors have an inordinate influence over the numbers.

Actually MSA's recommendation might be 50cm's. See no consistency.

[techieboy]

93 on driveby was just sucked out of my thumb. less is better.
95 on driveby seems to be the most common bottom at tracks these days.

Measured how though? There doesn't seem to be a "standard" method to take those measurements. Where I've actually been bollocked and given my drive-by readings, I've measured 101db (in a 98dB limit) at a couple of metre's above the track and 88.2dB at what's meant to be 20 metres away from the track. No consistency.

If the Tullet system passes the 105dB limit at Silverstone can he not claim that it meets trackday noise limits? He's not actually claiming it meets every track's noise limit. Likewise, does he claim to meet any European track limits? I don't know. Does the fact it's no good for Zandvoort mean it's not track safe somewhere else.

Whatever else, a silencers effectiveness reduces over time, so at some point it's going to fail a test even at a 105dB day somewhere.

[FLD]

They dont need to forsee track limits changing, they need to update their claims. If they want to continue the "meets track noise limits" claim then it should. If not then bin it off the website. Tullets are guaranteed for 12 months. I'd switched to a 2bular and not noticed the cat was fooked so I was outside this period hence I have to fork out for a new cat. What grieves me about this is that loads of this type have failed, they swapped some, know its a problem so switched supplier but I have to pay out. I will defend their fabrication as phenomenal quality and the service is pretty good. The performance is what lets the side down.