T O T A L Mufflerectomy...

[Andrei Rinea]

How about cutting off the Cat and the 2 mufflers (B4 Variant Passat TDI) ?
What would hurt except pollution? Is there enough backpressure from the turbo to make the engine run OK ?

Any opinions welcome!

 

[nicklockard]

Diesel engines do not need any backpressure to run. None.

Please don't do this anyway. There are plenty of effective ways to get power/torque increases without compromising air quality...

$0.02

 

[TDIfreak]

I've been driving for about two weeks without the cat after changing the turbo and downpipe. I'm gonna put the cat back for some noise and odour control. It smells bad without the cat, I can tell you.

 

[Andrei Rinea]

Ok... so you ran without Cat AND MUFFLERS? How was the noise? And how bad can the smell be? After all I could smell old trucks

 

[TDIfreak]

Ok... so you ran without Cat AND MUFFLERS? How was the noise? And how bad can the smell be? After all I could smell old trucks

Yes, straight exhaust from the turbo. The sound is... sharp. Now that I have the exhaust end turned down it's not bad at all inside until about 110 km/h. But the heads are turning too much and you have to crall at idle in parking halls etc.

It smells as bad when warm as it smells on cold starts.

 

[Mark Rudella]

I would recommend getting rid of the cats. A lot of people just cut the muffler off and think the sound is good. If you're trying to make power this way in this car, it's not going to help. Well, I should say, you may get 2 hp's maybe. I'm not totally sure though because I still have my muffler on and I doubt anyone has taken a before and after dyno run to see the increases. From what I've heard from some people, they think the car is too loud even with just the muffler off!!! I've yet to hear one for myself, so I'm no help in that department.
My final thoughts:
Buzz the muffler off, keep the cats, and keep the EPA happy!!

 

[killerjetta]

It smells as bad when warm as it smells on cold starts.

Is the diesel smell really strong, or a different smell?

I was planning on having a custom downpipe made so that I could take the cat in and out at will....sometimes you just wanna be loud!

 

[Deception]

I am running a straight exhaust right now (GHL 2.5" non-cat donwpipe, stock cat-back, no muffler) and it is indeed quite loud. Definitely a few notches in loudness compared to having a cat and no muffler. However, I didn't notice a significant increase in exhaust odour after putting in the downpipe. The noise is a little dronier and the turbo is REALLY high pitched (pretty sweet), but you'll get used to it. It's not for the faint of heart I suppose, but it's not as loud as say, a Honda Civic or Subaru WRX with a loud exhaust.

 

[Pcar993]

I just put my stock downpipe with cat back on. I was running a TT 2.5" turbo downpipe with no cat and stock cat back with no muffler. The turbo noise was sweeet but the smell was very bad. I had to put my stock downpipe and cat back in. Oh well.

 

[Deception]

The smell might be correlated with the quality of the diesel fuel in your tank. I'm not sure, but my exhaust doesn't smell too much different from what it did with the cat in place.

 

[ReKt]

I have done the mufflerectomy, from the last bend back. The pipe diameter is 2.25 or 2.5 stainless and I notice a whining (whistling) at idle upon initial start-up when the engine is cold, once warm it goes away, anyone with a similar experience or any thoughts??

 

[major-poser]

i have no muffler, no cat. and i love it, the turbo is CRAZY and the exhaust note for a 4 banger is lovely, of course it's gonna be a little loud but hondas with fart cans are louder! i love my no cat no muffler exhaust!!! it sounds CRAZY!!!! people think i have some crazy 10 second car with a turbo the size of my head, i think it's pretty funny! from my research, i've notice that cat's kill off any signs of high pitched noise like a turbo, and the muffler knocks off the low pitch engine noise. people who remove their cats that have a turbo charger or two, have a more pronounced turbo sound from their exhaust. i just love the raw sound of my diesel engine, most people disagree with me tho. but trust me there are alot louder things out there, any v8 with a aftermarket exhaust, any japanese 4 banger with a fart can, and every semi is louder than my exhaust. and the exhaust note is a deep growl, somewhat close to the growl of a 1.8t, but i like mine over the 1.8t alot!!! i wish you could hear it!

 

[turbobuilder]

The exhaust is much louder with a wastegated turbocharger than it was with a vnt turbocharger. As a result I'm now putting in a high flow muffler.

 

[mojogoes]

I agree totaly the sound i get is great no cat resonator or mufflers and with the 4-1 s/steel manifold i recon it hits an even higher note.
Just going off subject does anyone get/buy performance VW dec adition, there is a guy in there with a polo g40 conversions with 180bhp another one of tdi-rs's jobs

 

[AntonUK]

I agree it smells bad Iv noticed too. I have no cat but when I had no mufflers swell it was just to loud for me. It was ok at idle and cruise but when under loud it just sounded ridiculous! Iv put just a muffler on which has silenced out the turbo way to much but couple of days I’m having a high flow muffler put on. Hope that will bring back the turbo whistle without raising the level of engine too much.

 

[grimlock]

How about cutting off the Cat and the 2 mufflers (B4 Variant Passat TDI) ?
What would hurt except pollution? Is there enough backpressure from the turbo to make the engine run OK ?

Any opinions welcome!

Preferably leave the cat... That's what I did. Say goodbye to the deadweight mufflers.

Turbo spools faster, lose ~50lbs, and more interior drone, very little difference in sound/noise on the outside.

Richard

 

[Fazeey]

how is it with the max speed? i heard it decreases much after both, center and rear, mufflers.. Is that true?

 

[major-poser]

are you asking me? if so, it does get louder but i don't think it sounds bad, and it's not much louder than a semi, or a honda, they droan me out on the road, it sounds real nice when you get on it too! i love it man!

 

[Andrei Rinea]

how is it with the max speed? i heard it decreases much after both, center and rear, mufflers.. Is that true?

YYYIIIKES!!! Does this statement have anything to do with reality? (No offence man) I mean can the max speed go lower with mufflerectomy? WHY??!

 

[jnecr]

how is it with the max speed? i heard it decreases much after both, center and rear, mufflers.. Is that true?

YYYIIIKES!!! Does this statement have anything to do with reality? (No offence man) I mean can the max speed go lower with mufflerectomy? WHY??!

I think he means the volume of the sound...
But then.. I'm not sure

 

[1point9turbo]

hi, u guys seem to know what ur doin on this subject of exhaust...ok, im looking for a down pipe for and MK3 tdi...a 1998. i cant seem to find anything when i search the net for one...its all mk4...would i be able to use an mk4 downpipe? isnt it the same engine? please help me out and i thank you.

 

[Andrei Rinea]

Well I did it.
I took the cat off. (The mufflers were off a month ago)
The sound at startup and revving a bit in neutral is fantastic.
BUT!! At WOT and partial load the sound is unbearable I'd say. Everytime I pass a police car I am switching to idle (press the clutch in) to avoid a ticket or stuff...
Anyways I am going to put in a high flow muffler (I think it's called "cherry-bomb")

 

[david_594]

So the sound was good before you took the cat off, but after it was too much? So instead of putting the cat back you want to go with a pep-boys cheap aftermarket muffler?

You already know what the car sounds like with the cat on, and seeing as how you wanted louder we can assume that was acceptable. Why no do the environment a favor and just put that back on? Its probabily cheaper than buying the new muffler and you know what type of results you will get you... and a tree will thank you for it.