discussion Decat / downpipe no noise

[Salt]

Hi all. I'd like to ask for some advice. How clogged up does a petrol engine filter gets vs a diesel engine filter? Is it also a good idea to do a dp as the mileage increases to decrease back pressure on the turbo/engine? And if one did go this route, what are the options on the replacement. I wouldn't want the car to get any louder really. I see overseas high flow cats are available in 200 or 300 fell units. They do say sounds does get louder but I assume it's marginally louder vs the usual dp that gets installed. Essentially and hypothetically 😉 I'd like to do what's healthiee for the engine long term but not make the car loud. I also have an extended warranty on the car to take in to account. Advice welcome 😁

 

[PsyCLown]

My understanding is that a petrol catalytic converter can still get clogged but it is significantly less likely and far less of an issue compared to a diesel particulate filter.
A cat is still restrictive, so removing it also removes some restriction from the exhaust system and there is a bit of performance to gain by doing so.

If you're not looking for additional performance and do not want it to be louder and the cat is not clogged, I would leave it.

 

[KarshS]

It will get louder with any downpipe that removes the cats.

Maybe look into catalytic converter cleaning. Physically removing the cat and doing a high pressure clean. I think Steves Auto Clinic and a few others do this.

Not sure how these cat and 02 sensor stuff you put in your fuel tank works. If it even works at all.

 

[AshG108]

Damn dude,

Its a x40i, remove the CAT, do a DP and just add an extra resonator box if it is too loud however...best is to remove the CAT and let it breathe. You will end up loving the tone when the DP is done, very rare does someone not enjoy the symphony that this engine produces with a DP.

 

[Salt]

Damn dude,

Its a x40i, remove the CAT, do a DP and just add an extra resonator box if it is too loud however...best is to remove the CAT and let it breathe. You will end up loving the tone when the DP is done, very rare does someone not enjoy the symphony that this engine produces with a DP.

I just don't want the cold start normal driving in comfort kode to be any louder. I've got the MPE on.

 

[r0ckf1re]

I just don't want the cold start normal driving in comfort kode to be any louder. I've got the MPE on.

Just do it, it’s epic and addictive.

Visually your car is “loud” so complete the package. It’s not unbearable on comfort mode. Pure pleasure!


Sent from my iPhone using Tapatalk

 

[Holiman]

I just don't want the cold start normal driving in comfort kode to be any louder. I've got the MPE on.

Said no man ever. Lol. Just kidding. If you decat next option would be to get software to stop the loud cold start. It's a give an take situation.

Sent from my SM-S921B using Tapatalk

 

[AshG108]

I just don't want the cold start normal driving in comfort kode to be any louder. I've got the MPE on.

A decent downpipe from a reputable shop will have the car sounding bassy but calm on comfort and unleash the best when boosting and WOT.
But I think once its done, you will be all smiles no doubt. Even cruising on the highway, no drone or annoying humming from the footwell. In all honesty, I only had TMSS DP and Powerflow (XFlow) DPs fitted to my cars and all were great. Long distance drives were a pleasure and dare I say almost stock sounding when cruising.

 

[Teezoh]

It's a no-brainer bud. DeCAT it and get it under the belt, even with the MPE it won't be that loud.

P.S @Salt, saw the cabbie in the flesh like 2 days ago at Spar looking good man. Was in a bit of a hurry so could not wait around till you got back to the car.

On a side note: The weather here is awful, the roads are horrible and the people can't drive for shit...

 

[Salt]

It's a no-brainer bud. DeCAT it and get it under the belt, even with the MPE it won't be that loud.

P.S @Salt, saw the cabbie in the flesh like 2 days ago at Spar looking good man. Was in a bit of a hurry so could not wait around till you got back to the car.

On a side note: The weather here is awful, the roads are horrible and the people can't drive for shit...

I'm giving it some thought...😁

What...are you visiting up here? Pity didn't get to greet.

And yes, yes and yes. Point no 2 the reason I got rid of the run flats!

 

[Salt]

A decent downpipe from a reputable shop will have the car sounding bassy but calm on comfort and unleash the best when boosting and WOT.
But I think once its done, you will be all smiles no doubt. Even cruising on the highway, no drone or annoying humming from the footwell. In all honesty, I only had TMSS DP and Powerflow (XFlow) DPs fitted to my cars and all were great. Long distance drives were a pleasure and dare I say almost stock sounding when cruising.

Yeah...if I did get it done it would only be TMSS.

 

[Salt]

Anyone with a 140 and a dp done around JHB/East Rand? I'm very keen to hear in real life what it sounds like, especially in comfort mode under normal driving.

 

[AshG108]

Anyone with a 140 and a dp done around JHB/East Rand? I'm very keen to hear in real life what it sounds like, especially in comfort mode under normal driving.

Dude - message Nishen on here or on the whatsapp group and ask him to send you a few vids in the meantime as well

 

[Teezoh]

I'm giving it some thought...😁

What...are you visiting up here? Pity didn't get to greet.

And yes, yes and yes. Point no 2 the reason I got rid of the run flats!

Yeah, we're in the area I'll keep an eye out, have loads of stops to do before we head back on the 11th again.

 

[KR_19]

I've currently got a decatted downpipe with the MPE on my F30 340i. I'm in Cape Town but happy to share before and after videos with you @Salt, although it's hard to tell from videos vs actually being in the car.

In my view, the sound is perfect, I even thought about doing the midpipe but after hearing another M240i, I realized it might be too loud for the daily and highway driving.

I can confirm that the cold start was much louder after installing the dp. As someone mentioned, you can code out the cold start. I actually did that after initially adding the dp but after a few months I actually missed it... so now it's back on and on occasion it sets off an alarm or two in the shared basement parking in the mornings lol.

Sent from my SM-F956B using Tapatalk

 

[Teezoh]

I've currently got a decatted downpipe with the MPE on my F30 340i. I'm in Cape Town but happy to share before and after videos with you @Salt, although it's hard to tell from videos vs actually being in the car.

In my view, the sound is perfect, I even thought about doing the midpipe but after hearing another M240i, I realized it might be too loud for the daily and highway driving.

I can confirm that the cold start was much louder after installing the dp. As someone mentioned, you can code out the cold start. I actually did that after initially adding the dp but after a few months I actually missed it... so now it's back on and on occasion it sets off an alarm or two in the shared basement parking in the mornings lol.

Sent from my SM-F956B using Tapatalk

On the cold start topic, I noticed on our vacation that the time here in Kempton is way less than it is down in Cape Town. At home it runs an average of around 40-50 seconds while here it only lasts around 20. I pop off around 5 alarms in the complex we're staying at every single morning too, generating smiles instead of drama so that's a relief.

 

[Salt]

Thanks gents. Any louder than currentl start will not bode well for me 😁. I wouldn't mind an even more aggressive sound when in sport and going wot...but not more in comfort or at start up. And I like the current level of sound at cold start. The main reason I was considering this is just engine health. I did the dp on my 320d for the same reason. I realize I'm being difficult here but I have to consider my surroundings and circumstances. Perhaps one of those 300 cell catted down pipes. Will I need a tune if I did any sort of dp? I'd prefer not to.

 

[AshG108]

Thanks gents. Any louder than currentl start will not bode well for me 😁. I wouldn't mind an even more aggressive sound when in sport and going wot...but not more in comfort or at start up. And I like the current level of sound at cold start. The main reason I was considering this is just engine health. I did the dp on my 320d for the same reason. I realize I'm being difficult here but I have to consider my surroundings and circumstances. Perhaps one of those 300 cell catted down pipes. Will I need a tune if I did any sort of dp? I'd prefer not to.

IIRC - the M140i has a resonator on the exhaust, just under the front seats (positioning). It can be possible to maybe do the DP and fit a slightly larger resonator perhaps?

 

[Sabretooth tiger]

IIRC - the M140i has a resonator on the exhaust, just under the front seats (positioning). It can be possible to maybe do the DP and fit a slightly larger resonator perhaps?

or remove even that too and become the most well-known neighbour

 

[Teezoh]

The cold start is there to warm up the CATS faster so if you go catless just get the cold start coded out since there is no point in cold starting at all anymore. I left mine on for personal preference only, the louder the better. Will be going straight out sometime this year, just looking for someone who needs the MPE.