Mufflerectomy and Catalectomy Question


Veteran Member
Sep 28, 2008
2000 Jetta TDi, 1981 Chevrolet LUV Diesel! Non-turbo :(
larithmos said:
Adonis, I noticed your tint comments in your profile. I just got a ticket for that... in Iowa. Cop went to his car and look up the MI regs and gave me a stinkin ticket.

...on stinky exhaust, the worst exhaust smell is from and oldish gas cars when the car is cold, that stuff is about as acrid as it gets.

Maybe true unless it is plugged, then there is a very noticeable improvement.
^^Agreed. I can't tell the difference between ULSD and LSD.

I love your sig by the way lol.


Veteran Member
Feb 17, 2009
Springfield, MO
2005 GLS TDI
sqhschief said:
Just a quick note to update those who were asking.

I did go ahead and cut off my catalytic converter. I noticed it was very clogged. I went ahead and welded a pipe on till my high-flow gets in.
I noticed a fairly generous power response increase. I also could tell my tdi now smells like a semi-tractor with a strong "diesely" smell, and smokes more. Lastly, this coupled with the muffler removal makes for a really loud turbo spooling sound, I love that. I just hope it wont muffle any of that sound with the new high-flow.

Oh one more thing. I noticed I get 4-5 extra mpg. My catylytic converter must have really been clogged...
Speakin of cats, whats the average life span of one? I've got 71k on my tdi.. getting clogged...? Si or no? And when you says you gained mpg are we talking all hwy or city? If i can gain that, hell yeah i do it..
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New member
Nov 5, 2009
04 jetta stock 70k
simple questions that need answered

can proforming the catectomy harm the motor in any way.... cuz i was looking through the posts and some people are for it and some are kinda like "well idk"....????? and what is a "ventectomy"


Top Post Dawg
Jul 4, 2007
Blaine, MN
2012 BMW X5 35D
First off, know that the discussion of the removal of emissions equipment is strictly prohibited on the forums at the discretion of the ownership and management. Certain members are very vocal against it, I don't care either way. Its your car, do what you want.

That said, technically speaking, removing the cat is not going to harm the motor. But in your case with your 2004 BEW engine, the small turbo tends to have boost creep problems when you increase exhaust flow and reduce back pressure. This could be harmful to the turbo/engine if not controlled properly. Exhaust mods are not going to give you any HP gains, so save it for when its actually needed. Tuning, fueling and a turbo upgrade would be prerequisites to exhaust mods on a BEW.

As for ventectomy, we have this wonderful button up above that says "Search," give it a try.


Moderator at Large
Jun 16, 1999
Brampton, Ontario, Canada
2006 Jetta TDI
The legality (not) of rendering the catalytic converter inoperative has already been mentioned in this thread ... and for those who have been yelling at us that this is a "new" policy, would do well to go back and look at the date on the post at which this was first mentioned in this thread. Pre-dates DPF, pre-dates common-rail, etc.

The correct course of action - use a high-flow diesel catalyst - has also been mentioned in this thread.

The rest of it is up to you, to do the right thing.

Bear in mind that since this topic was started, California has a new policy that pretty much requires the *original* catalytic converter to be used, in order for the vehicle to pass inspection. The high-flow diesel catalyst is no longer an option if you have to deal with California emission inspections.

Do I like or agree with this? No. But, it is what it is.