[hokiedood]

Can anyone recommend a high-flow catted DP that's on the quiet end? I want the performance but I don't want the noise. No CEL guarantee would be great.

[conejodenieve]

I can't comment on how quiet it is since I don't have any of the stock exhaust anymore but I've had the Active Autowerke Catted DP for about a year now and still no CEL.

I will say though, that my exhaust is still valved and whenever I come across cops while driving, putting it back into comfort has kept me from getting unwanted attention thus far.

EDIT: I have AA Catted DP, Dinan Midpipe, and AFE Axle back for reference.

[Skyhigh]

Interesting seeking.

High-flow & quite are 2 mutually exclusive properties if you ask me.... high velocity gases make noise. The way to reduce noise is to reduce their velocity, hence to introduce some sort of restriction. Some people reduce noise effectively with additional resonators, after the downpipe. I am personally sceptical about the claim that this doesn't restrict airflow at all, even if minimally, but it is an option.

I must say I have never heard "complaints" that any specific high-flow downpipe doesn't change/increase the sound/noise (usually this is a wanted side-effect).

My only advise would be to go with the most cells you can find, whilst still less-restrictive than the stock. The less cells - the noisier. (Another reason why I did not even consider 200 cell, apart from the fact that most come with CEL)

[Eddie_440i]

Hello !

I am driving with Wagner tuning 300cell HJS downpipe with MPPSK.

The sound is perfect both in open mode and closed mode. Would say perfect for daliy driving but when you want sound and are on car meetings just open up those valves

NO CEL with this downpipe

[e_b_d_i]

Originally Posted by Eddie_440i

Hello !

I am driving with Wagner tuning 300cell HJS downpipe with MPPSK.

The sound is perfect both in open mode and closed mode. Would say perfect for daliy driving but when you want sound and are on car meetings just open up those valves

NO CEL with this downpipe

I have an Akrapoviç DP on the way (thank you Mike@X-PH!) which will be installed with stock exhaust. I'm guessing any of the HJS cat options (Wagner, HJS, Akrapoviç) will yield similar results, though they'll all dampen less noise. Unfortunately, they're also the most expensive options.

[Skyhigh]

That's the thing. Sound/noise is subjective.
I am also driving a 300 cell HJS cat in an Akrapovic DP, together with the MPPSK exhaust (which is a straight pipe in sport mode, with valves open).

I must admit in Sport (valves open), it is a bit too loud for my liking. It is tolerable.... after the initial ear-shock, but if I didn't have the option to turn it down by closing the valves for relaxed cruising, I would definitely be looking at modifying something.

I suspect in combination with the stock exhaust, it would be much milder and more tolerable. (But I still don't regret the MPPSK exhaust for a second)

[jjhebigscreen]

I have Wagner 300 cel Hjs cats on a stock exhaust and Bootmod3 stage2. It is maybe 20% louder than stock when you start car with windows down. To me it sounds perfect. Not to loud at all. With the windows up it is maybe 10% louder. Hardly noticeable but again a pleasant sound.

[disintegrator66]

Unfortunately Wagner no longer offers the 300 cell HJS catted downpipe. Bummer...

[mike@x-ph.com]

Originally Posted by hokiedood

Can anyone recommend a high-flow catted DP that's on the quiet end? I want the performance but I don't want the noise. No CEL guarantee would be great.

The active autowerke is the quietest one since it got more CEL than the generic 200 CEL cats used with most other brands.

[cxmplex]

I have the active autowerke one and it is NOT quiet. It might be the quietest high flow downpipe, but it's definitely not "quiet" in general.

Cold starts are very loud with the AA catted DP.

[Skyhigh]

Can we not just summarise that 300 cell DPs (plenty out there, most based on HJS cats) are to be expected to increase noise/sound less than 200 cell, which in turn are significantly less noisier than catless DPs?

I would be really surprised if there is a noticeable (for the naked ear) difference in noise level between two 300 cell or between two 200 cell DPs....
Best case they could modify the sound slightly differently, but dB-wise...... Extremely unlikely to vary.

[dmanb2b]

Originally Posted by cxmplex

I have the active autowerke one and it is NOT quiet. It might be the quietest high flow downpipe, but it's definitely not "quiet" in general.

Cold starts are very loud with the AA catted DP.

I don't find it to be that loud and once you are tuned, cold start is pretty easy to turn off. I hear zero difference when cruising unless you are above 25% throttle.