[Mk2] [Turbo] Reducing the noise from Exhaust and Decat

[silver surfer]

I recently purchased my rev 2 tubby and am loving every minute of it. I have just replaced the stock air intake with an Apexi induction kit, fitted a CAT replacement down pipe and a mongoose exhaust (bought this as it looks fairly stock and was under the impression that it was a fairly quiet exhaust). All work was done by Pacific Works who did an amazingly fantastic job Performance has definitely improved noticeably

Now the question...Does anyone else that has upgraded to a decat and performance exhaust miss the lovely stock sounds from the winding turbo? All I seem to hear now is the boom from the exhaust and down pipe. I somewhat miss that silent effortless acceleration

Is there any way of quietening the exhaust / down pipe down somehow without replacing the parts?

[Harold]

You could put a bung in the exhaust, but this may affect performance as you're placing a restriction on your very free flowing system.

[silver surfer]

Thanks for that, I was thinking of a bung but ideally I don't want to limit performance. Was thinking of replacing the decat with a gutted original CAT (something Luke at Pacific did recommend). But I would lose some performance and the original CAT weighs a tonne!

Are there any other solutions or ideas that could be explored? Is the Mongoose supposed to be quiet or is that myth? If it is just the exhaust I could replace that (one day), as it is I'm pretty sure it is the downpipe causing the majority of the noise.

[dantheman]

i do believe the mongoose overall is quieter but obviously perceived noisiness varies at different engine speed and load for every exhaust system so it can be hard to say sometimes.

The biggest difference as you suspect is the CAT. On my old car a CAT + custom exhaust = 98db. decatted it went up to 104 db. You'll be hard pushed to find a cat-back exhaust system that can undo a change of that size.

tbh you need to think about your priorities. Theres a tradeoff between performance and comfort. If you want performance, you cant complain that its noisy or the ride is too harsh.

[silver surfer]

This is true.. I may swap the downcat to an original cat with gutted internals to get some quietness back.. or I may just stick it out and man up

[Super_red]

I have found on other cars that gutted cats make a horrible noise since they are not designed to be that way, it can make the car sound very poorley.

I have a decat and mongoose ready to go on mine and am currently loving the stock sound as like you say is quick but quiet so its even more of a suprise to people. I dont want it to get to loud. I think the mongoose might be off the cards now if it is loud and I will stick to a much larger rear box setup or 2 boxes inline rather than the 2 paralell with the mongoose.

That said a friend has a Saab turbo 2.0 with a powerflow exhaust and its beutifully quiet, no cat as standard and only a single box on the exhaust.

My last thought was a custom setup with one very restrictive queit silencer and one very loud one in paralell with an electric switch to divert from one to the other, would allow me to drive round most of the time in stelth mode, could even program the ECU to swap over automaticly if power were required.

[silver surfer]

As you say I do miss the standard sleeper effect i.e. effortless (and noiseless) performance on tap. It went a lot faster than it sounded and now it sounds a lot faster than it goes (even though it does feel faster) if that makes sense

I don't think it's the mongoose exhaust making all the noise, personally I think the exhaust does look gorgeous it looks like the stock exhaust should have looked, I think it's more the downpipe and induction kit making the majority of the sound (though obviously the exhaust does make it's own sound). The exhaust is louder at idle than it is in use strangely enough, it has more of a deep burble than a loud boom with some exhausts.

On the note of the induction kit - it sounds amazing at speed, makes a lovely sucking sounds when the turbo is spooling up, around town with the odd throttle blip it doesn't make as much noise, either that or it is drowned out by the noise of the downpipe and exhaust don't get me wrong it's not as loud as some other peoples exhausts (even with the downpipe), it's just a little too loud for my liking. Ah well will probably need to get used to it.

[djpkins]

dynomat and extra carpet will help...

[Driftlimits Performance]

I like the noise of a stock exhaust and decat. Rorty yet sensible.

Thanks for the kind words!

[silver surfer]

Fully deserved mate and I'll see you tomorrow for some further advice and work!

What is dynamat? Googled it looks like an American company has anyone used it?

[djpkins]

just sound deadening...used a lot in speaker wells but works well in sound insulating panels etc aswell....you would fkn sht a brick if you fitted polybush engine mounts, if you think the dp drone is annoying that is.

[mazmilly99]

just sound deadening...used a lot in speaker wells but works well in sound insulating panels etc aswell....you would fkn sht a brick if you fitted polybush engine mounts, if you think the dp drone is annoying that is.

That the truth! Get some Dynamat mate.

[silver surfer]

I set off two car alarms yesterday with the deep drone from my down pipe!

Considering that's with a quieter exhaust I am definitely a bit shocked

Call me old but I like more bite less bark not vice versa. But, I'm learning to live with it as all is forgiven when you put your foot down and things rapidly turn in to blur

[mrfil13]

When I had my reviews I had a gutted cat (by skywalker) and a dep 2 exhaust non profit version, the sound was perfect for me, not to loud and could still hear the turbo.

[slipping clutch]

I used to have a mogoose fitted to my rev 1 turbo - it wasnt until I put a decat on that it became quiet loud, I believe if you want to reduce the noise and dont want to put bungs in the exhaust you may well have to go back to the catted down pipe. BUT I would suggest before you do that running it with the decat and mongoose and refitting the stock airbox and see if that gets the decibels down to your prefferd taste - You can get aftermarket performance panel filters to fit the stock airbox.