I've just had a 3" turbo back decat straight through milltek fitted and mapped to my 2.5 and it is LOUD!

I chose the milltek because everyone said it was relatively quiet. Don't get me wrong I love the sound and the turbo whistle but when cruising it makes this very loud drone which just fills the car up. You have to shout to be heard.

My previous 2.0 had decat up pipe, prodrive sports cat and back box and gave a nice burble, sounded great when giving it some but didnt intrude on the motorway.

The new one is so loud it hurts.

I changed the backbox back to the prodrive one, better round town but it still drones really loudly at about 3500rpm. I fitted the original centre section back in to see if that would help, better again but that still drones.

Is this all down to the decat? Do i pay the extra and have a sports cat fitted?

BTW I realise that these changes are affecting flow but it is just for testing to see which section is the problem.

Anyone ever had both milltek decat and sports cat to compare?

Cheers
Chris

 

Not to compare but I've done a few track days and mine (3" with sports cat) is usually one of the quieter cars out there

 

I had this set-up on my STI. Believe me considering there are no cats it could be louder!

 

My STi RA is fitted with Milltek 3" cat replacement downpipe, cat by pass centre section and rear silencer.

During 2007 the car has been noise tested at various hill climbs/sprints and the maximum db produced at 3/4 revs was 96.

Passed noise test everytime + I was "surprised" how unobtrusive the sound is inside the car (bearing in mind it has less soundproofing that some Imprezas).

Any use?

Richard

 

Cheers guys,

At idle or stationary revving it just sounds great with a nice turbo whistle. It is only when under pressure that it gets unbearably loud. Doesn't seem to be leaking anywhere but it is hard to check it when boosting if it is stationary!

Really confused as I thought the milltek wasn't supposed to be that much louder than a ppp setup.

Chris

 

Have you got the centre resonator box fitted?I ony get a deep roar when flooring it,but motorway driving is not over loud.

Merv

 

Mines got the miltek d/pipe,centre section with no cats and a prodrive back box and I dont find it that bad.Tootling around its very quiet until you give it the beans! I suppose its what your used to and personal preference but me personally I love it!!
Andy

 

I have a very small resonator on the mid section.

I still get the drone with a prodrive backbox and my original mid section with the big resonator.

When you are driving around it is nice then you floor it and it sounds great!

But the problem is on the motorway. Lets say you are at 3-3500rpm in 5th. Maintaining speed or accelerating you floor it and you get this really loud drone. It isn't a case of not being used to it, it is really loud. You have to shout to hold a conversation.

Compared to my old setup which didn't intrude at speed but still sounded good when you floored it, this is much much louder.

If that is what milltek decats are like then fair enough, I will look at getting the sports cat. Its just I was expecting something a bit quieter when cruising though.

 

i have a 3" pulse extraction system from tsl and its not louder than the firestorm. I would think its the lack of a cat. Sports cat seems the best option imho

 

I've got a 5Zigen and trust me this much louder than the Miltek but gives a very deep rumble which I love

I've had to add extra sound proofing to the boot and I normally drive with the window open a little as this seems to releive the droning in the cabin.

 

I had an afterburner decat with ninja box. This was non-resonated and it droned, about 3k RPM. Did you say yours has the resonator?

What about a bung for the motorway?

My current system is loud, but with the bung in it is even quieter than the revolution system i feel. Best of both worlds.

 

I've got the turbo back 3" decat Milltek on my Spec C and it's barely louder than standard just tootling about, I wouldn't say it was anywhere near anti-social at full chat either!

 

What is the shape of the downpipe? Is it a straight pipe with no silencer section? It is possible to have a decat downpipe with or without a silencer.

A sports cat downpipe will always have a silencing element, being the increase in size of the pipe to hold the cat, and the cat itself.

I have a full sports cat Racebox system from Scoobyworld. My centre pipe does not have a resonator, so on full power in top gear motorway work there is a drone. That was my choice.

It may be worth getting yourself to a local meeting to have a listen to what other people have, maybe swap pipes for testing. Lots of people have Miltech so you should find someone to help you get the setup you are after.

 

OK think i've got it sorted now. Spoke to Phil at Milltek today and asked for his advice. According to milltek their sports cat has a huge effect on the amount of drone but it should still sound good when giving it some.

Have ordered a sports cat with my tuner and he has agreed to do it at the difference in cost.

Chris

Oh luminous, it is a straight through downpipe with no silencer.

 

Yeah, that would do it....

Hope you like the end result, I love my sports cat system