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Anyone running full decats? how bad is the extra noise and smell? Trying to decide on full decat or just gut precats thanks

My old B7 S4 was decatted and I plan to do the same to the RS.
The S4 was loud as hell and a bit smelly but I soon get used to the smell and I never really got tired of the racket it made! The Mrs absolutely hated it, too loud for her.
The set up was 2.5" custom DP's and non res Miltek cat back. Worth noting when the DP's were added I did notice more rasp high up on the revs.

The RS has gutted pre cats and stock cat back just now so it's really quiet compared to what I'm used to. I'm considering binning the resonators for a bit more sound until I decide on what system to get.

It's good for a giggle but otherwise I don't find a full decat suiting the car much. It's supposed to be at least somewhat grown up and civilized - not a scoobie or EVO driven by a chap with his cap on backwards. The smell is worse for the people behind you in a queue, not so much an issue driving the car. It's also likely to smoke a little without any cats. It's just unnecessary.

Keeping the main cats and fitting a suitable exhaust is way preferable. You can make it more than loud enough whilst keeping the main cats and avoid most of the "clatter" sound.

I have Milltek decat pipes and a non res valved exhaust. There is no smell other than a normal exhaust and it's quiter than with OEM cats and the same exhuast. Valves closed helps.

But... flames!

http://www.youtube.com/watch?v=8J3E5IebpkM&t=0m56s

That's full milltek, non-res, non valved. I wish I'd kept valves tbh simply for when you do want it quiet but when you want it loud, it's like the devil gargling nails.

Personally I'd say if you've got a friendly MOT place, get it done (but keep a valved system). The sound is amazing.

Covkiller wrote:I have Milltek decat pipes and a non res valved exhaust. There is no smell other than a normal exhaust and it's quiter than with OEM cats and the same exhuast. Valves closed helps.

Really? That sounds interesting. I have a non res valved milly I find it just enough was worried decay might tip it over the edge

Serious, my little girl and even the wife thought it was quieter.

No cats in mine at all, doesn't sound loud to me, noise isn't obtrusive inside the car whatsoever.

Iv heard a fully decatted RS4 at full chat and it was scary loud from the pavement. Literally everyone was turning around and looking and not in a goodway. Sounded like a unsilenced racecar and didnt suit the car imo the low frequency bass was lost , which I love about the car. It was literally just noise, I think a balance needs to be struck with naturally aspirated cars as they can lose some of the character when going fully straight through and becomes just loud noise.

On a turbo charged car I can understand , because the turbos muffle the sound compared to NA cars and least back pressure is mostly better. Dont NA engines require some form of back pressure?

No that's a myth. (Unless we're talking about two stroke engines).

The vortex exhaust on my car when I bought it was effectively decatted, with no centre silencers, just backboxes. It was way too loud for me (and the wife and the neighbours), and droned pretty badly around 2k revs. The first few times I drove it, I've got to say that the fumes/smell did get to me a bit too. Put a grin on my face when driving on my own somewhere I could give it the beans, but just couldn't live with it.

I've now got OE cats but precats deleted, x-pipe centre (no resonator), and OE backboxes with flaps stuck open. The volume level is just right for me (probably too quiet for some), no drone, and no smell.

Have you considered getting someone to cut the precats out completely, retaining the OE cats, rather than gutting them? Should mean that you have no grief at MOT time too, whilst still getting some performance benefit.

^I was thinking about X pipe. Is there much tone difference between the X and H? Don't suppose you've got any sound clips?

ASC wrote:^I was thinking about X pipe. Is there much tone difference between the X and H? Don't suppose you've got any sound clips?

Sorry, no sound clips of mine. I did find some on YouTube though when I was investigating before getting it done.