De-cat advice please
Discussion
Decat and std back box for me every time over here. sounds fantastic and the std back box is very free flowing, only expensive sports pipes come close and most flow less. Might be rare though these days with the factory problems, in which case ...
If you're feeling a bit flush call silverstone performance and ask about their rear box .. big hp with proper cerbera sound. boss cerb raves about his.
If you're feeling a bit flush call silverstone performance and ask about their rear box .. big hp with proper cerbera sound. boss cerb raves about his.
ajp4.2 said:
I posted last week about what sports exhaust to go for. Many thanks it looks like the Act big bore is favorite. For another option Has anyone ever de-catted and used a standard back box???? What would advice be on that. I think de-cat and sports rears would be too much for me!!
Decat & std back box is v good as latter has much larger volume than sports silencers so the extra flow you get without cats isn't strangled by higher back pressure. Not as loud of course but i once heard you can get too much noise.... I had larger bore tailpipes put on the std back box which added a bit more bass and fills the body cut out better as well.
Hello ajp4.2,
as you know our car is now fully deccated and has a sport zaust.
When we brought the car it was just decatted, it was a nice noise but the sport zaust gave it the extra bit of noise!
But still the noise of the decat's was very noisy! and it will pop 'n' bang like a good'un
as you know our car is now fully deccated and has a sport zaust.
When we brought the car it was just decatted, it was a nice noise but the sport zaust gave it the extra bit of noise!
But still the noise of the decat's was very noisy! and it will pop 'n' bang like a good'un
I run a decat and a standard back box on my 4.2 The Db levels are tested before every sprint generally at either 0.5m or 1m from the tail paipes at 45 degrees from the end of the pipe depending on the circuit.
my readings vary between 99 and 102 depending on the distance of the sound meter and the meter itself. The car is not too loud but is nice when on full throttle. Most tracks are 100 Db so you will be borderline if you want to go off road and play.
You can also get bolt on extra silencers for track work at circa £100 which takes about 5Db off
Hope this is helpful
jes
my readings vary between 99 and 102 depending on the distance of the sound meter and the meter itself. The car is not too loud but is nice when on full throttle. Most tracks are 100 Db so you will be borderline if you want to go off road and play.
You can also get bolt on extra silencers for track work at circa £100 which takes about 5Db off
Hope this is helpful
jes
jesfirth said:
. . . The Db levels are tested before every sprint generally at either 0.5m or 1m from the tail paipes at 45 degrees from the end of the pipe depending on the circuit. jes
Jes - is this standing behind the pipes at the distances and angle you mention or standing side on to them - if you undertand what I mean? Thanks
Hi Keithyboy,
a sound test works like this. there are 2 scrutineers.
the first stands by the open drivers window and asks you to set the revs at 2/3 max - so around 4600. He watches the tacho and when the revs are correct he raises his arm and the 2nd bloke the tester presses a button and takes a reading.
The second tester, the guy with the meter stands just behind and to the side of the car(so the sound does not bounce back off his legs giving a false reading)
He holds the meter which is taped to a stick of a predetermined length usually either 0.5m or 1.0m long (it depends on the track)
the end of the stick is placed against the end of the tail pipe so therefore the meter is the correct distance from the end of the exhaust.
the stick is held at approx 45 dgrees from the end of the tail pipe angled towards the outside of the car and is also usually tilted up so that the tester does not have to bend down-poor love.
they then repeat the exercise on the other exhaust if you have 2 and take the higher reading of the 2
The whole process takes less than 1 minute
the key to getting a fair test is to ensure that the revs are stable so that there is no back firing or popping as this massively increases the readings.
Some circuits also have drive by tests. Goodwood and snetterton are 2. These are a real nightmare as they are usually on the straights by the pit wall taking readings when you are on full acceleration. I normally just try and keep on the other side of the track away from the meters when these are being used
a sound test works like this. there are 2 scrutineers.
the first stands by the open drivers window and asks you to set the revs at 2/3 max - so around 4600. He watches the tacho and when the revs are correct he raises his arm and the 2nd bloke the tester presses a button and takes a reading.
The second tester, the guy with the meter stands just behind and to the side of the car(so the sound does not bounce back off his legs giving a false reading)
He holds the meter which is taped to a stick of a predetermined length usually either 0.5m or 1.0m long (it depends on the track)
the end of the stick is placed against the end of the tail pipe so therefore the meter is the correct distance from the end of the exhaust.
the stick is held at approx 45 dgrees from the end of the tail pipe angled towards the outside of the car and is also usually tilted up so that the tester does not have to bend down-poor love.
they then repeat the exercise on the other exhaust if you have 2 and take the higher reading of the 2
The whole process takes less than 1 minute
the key to getting a fair test is to ensure that the revs are stable so that there is no back firing or popping as this massively increases the readings.
Some circuits also have drive by tests. Goodwood and snetterton are 2. These are a real nightmare as they are usually on the straights by the pit wall taking readings when you are on full acceleration. I normally just try and keep on the other side of the track away from the meters when these are being used
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