Mufflerectomy and Catalectomy Question

[sqhschief]

I have done the "mufflerectomy" on my '00 Jetta TDI. I am contemplating whether or not to perform a "catalectomy", that is to remove the catalytic converter and straight-pipe it. I am curious what differences I would notice in doing this. Please answer each question. I'd love answers from people who have done a mufflerectomy and THEN a catalectomy. Acoustics, louder, louder spool? Smoke more? Obviously lowers EGT. Any cons besides enviromental? Thanks!

 

[ibanix]

You'll get more 'diesel' smell, trust me =)

 

[sqhschief]

You'll get more 'diesel' smell, trust me =)

Yeah, I'm probably going to be doing this soon just to lower my EGT's and hopefully get a longer lived turbo.

 

[Mark Rudella]

I'm not sure if your state requires yearly inspections or not, but if it does, and you cut out the cat, you may fail. If you really want rid of it, I'd take it out, ram a rod through it to hollow it out, and put it back on.

 

[mike]

It will likely be a little louder. I think the cat isn't much of a back pressure issue as was the muffler.

 

[streeker02]

It will likely be a little louder. I think the cat isn't much of a back pressure issue as was the muffler.

Neither the cat nor the muffler are as much of a back pressure issue as the turbo itself.

 

[GoFaster]

Let's keep things in this forum at least quasi-legal, m'kay?

 

[mrchaotica]

One difference you'll notice is that people like me will be pissed off at you for being such a short-sighted, selfish bastard!

 

[midairmark]

I would like to do the same to my 01 Jetta. With the mufflerectomy, what exactly did you use/or do? (size pipe, adaptor, or use pipe expander and slip into straight pipe?) thanks! I am waiting for a warm day to break out the zaw saw. Please keep me up to date on your catectomy decision and what you used there as well, plus your mileage increase thanks!

Mark
newbie

 

[sqhschief]

Let's keep things in this forum at least quasi-legal, m'kay?

My state doesn't do inspections. And like I posted originally, I am just wondering what the results of doing so would be. I haven't done it. Also what the heck is wrong with the site today? I can get it to load half the time.

One difference you'll notice is that people like me will be pissed off at you for being such a short-sighted, selfish bastard!

I'm sorry, I didn't think I asked for your personal opinion, nor was this thread started to emote questions, statements, or opinions, of "green house gasses" or other emissions. Notice in the OP where I said "BESIDES ENVIRONMENTAL"?

I would like to do the same to my 01 Jetta. With the mufflerectomy, what exactly did you use/or do? (size pipe, adaptor, or use pipe expander and slip into straight pipe?) thanks! I am waiting for a warm day to break out the zaw saw. Please keep me up to date on your catectomy decision and what you used there as well, plus your mileage increase thanks!

I actually cut my own muffler off then had a shop weld on my strait pipe for me. I had them angle it out the back exactly like to original was so I don't get soot all over the back of my car. If I decide to do the "catalectomy" I will probably do the same, cut it and then let them weld on the new pipe. I'll update you if I do it.

 

[GoFaster]

The illegality of removing a catalyst is not dependent on whether your state/province has a periodic inspection program.

 

[Bob_Fout]

High flow cat is the answer They're $120.

 

[Tbirdtree]

High flow cat is the answer They're $120.

Agreed.

 

[sqhschief]

The illegality of removing a catalyst is not dependent on whether your state/province has a periodic inspection program.

I'm not trying to discuss legal issues here.

Quote:
Originally Posted by Bob_Fout
High flow cat is the answer They're $120.


Agreed.

This is the kind of answer I was looking for. I know the laws and need not be reminded.

 

[velociT]

My MPG's have gone up at least 2-3 after the intake and downpipe were installed (took out the cat).

 

[larithmos]

Bump.

 

[sqhschief]

I spent a few days driving my 2000 Golf with no cat while I was working on some replacement pipes and the car felt quite liberated at higher rpms. I cut the front off the cat and at 160k it was not in good shape, almost no light was getting through. The car runs better, so it has been off since.

My car used to smoke a lot under acceleration too... now I feel like my chip/turbo/injectors are in a much better balance as there is no real smoke to speak of.

I suspect this will be the condition of mine also as I have 158 grand racked up so far.

My MPG's have gone up at least 2-3 after the intake and downpipe were installed (took out the cat).

This is what I'm hoping for whether I go with a high flow or just cut it. I may cut it, and if its really bad go ahead and order a high flow. If its good I may weld it back on her, we'll see.

 

[sqhschief]

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...

 

[oldskool1963vw]

I went ahead and welded a pipe on till my high-flow gets in.

Where did you get the high flow cat from??

 

[redlinedave]

Dont bother,just smash the guts out of the old one and run
a holla back cat

 

[UFO]

Ugh, I hate that diesel exhaust smell. At least ULSD is better than the old "LSD" stuff, and everyone at least has to use ULSD. Better yet, burn biodiesel instead.

 

[Shawnz]

Is there a trick to the muffler removal to minimize the soot on the car?

My car is all stock but being VW's cruel joke (White TDI), the back of my car seems to consistently find a steady supply of soot on it.

If I move the turn down closer to the bumper and make it less vertical will it help? I was thinking of recycling a turn-down and maybe even a Borla straight-through muffler left over from my Mustang.

What size is the stock pipe? My muffler etc is all 2 1/2".

 

[larithmos]

Bump.

 

[velociT]

Getting the exhaust out past the bumper a little should help.

This is the answer.

You'll also notice less resonance when you extend the pipe out the back of the car.

 

[andreigbs]

Agreed.

X2. Diesel high-flow cat, with a larger SS downpipe and straight exhaust from the cat to the back, then add a nice SS twin tip and you're golden.

 

[willysrule]

Anyone know where this $125 high flow cat can be found?

 

[Tbirdtree]

TDIparts.com Kerma.com
The 2.5" is about $150
not sure how much for a 2"

 

[nokivasara]

IIRC there is a cat flow chart somewhere on this board, the back pressure was next to nothing.

I have gutted catalysts on a gasser and my old tweaked Passat TD and there was no change in performance, I clocked a few runs 80-120km/h in fourth gear before and after. The mileage remained the same too.
The turbo whizzle was louder though

 

[sqhschief]

This is the answer.

You'll also notice less resonance when you extend the pipe out the back of the car.

Yeah this is what I did when I performed my "mufflerectomy". It helped the build-up of soot on the back of the car.

IIRC there is a cat flow chart somewhere on this board, the back pressure was next to nothing.

I have gutted catalysts on a gasser and my old tweaked Passat TD and there was no change in performance, I clocked a few runs 80-120km/h in fourth gear before and after. The mileage remained the same too.
The turbo whizzle was louder though

Yeah, gotta love the loud whistle!

 

[sqhschief]

Haha

Ugh, I hate that diesel exhaust smell. At least ULSD is better than the old "LSD" stuff, and everyone at least has to use ULSD. Better yet, burn biodiesel instead.

Your kidding right? The following photo sums up my view on this .