Catalytic Converter Bypass Installation

[mowog63]

Hi All,

This is just me passing on some of my experiences with my installation of a Fabspeed catalytic converter bypass pipe (test pipe).
The purpose of this post is to add any knowledge I can pass on for folks thinking about/attempting this in the future.

I read a lot of posts through my searches to see what types of issues/challenges others had run into and prepared ahead of time.

Let me preface this by saying I've owned a Dremel for around 20 years and have found it useful about twice - I hate it.
But for this job, the Dremel, the quick change holder, and the metal cutoff discs that they sell actually worked perfectly for this job.
All in, the entire job took me about two hours.

I used:
- hammer
- cold chisel
- Dremel with quick change holder and 5 metal cutoff wheels (used them all)
- long punch (to tap out the cut bolts)
- various 13mm wrenches
- eye goggles
- face mask - 3M breather (I stupidly didn't use it, but if I had to do over, I would)

In anticipation that the O2 sensor would break or need to a severe mauling to remove it, I bought a new Bosch Universal sensor for this job as well.
Mine came off without a complaint, by dumb luck...I put a 22mm open ended wrench on it and it wouldn't budge. Then I sprayed it with some P/Blaster on a cold engine and the second try, 5 minutes later, it came loose!
I can see why a special 22mm O2 sensor socket would be handy.

I didn't bother spraying the nuts/bolts with any penetrating oils at all knowing that I was going to cut them all off. Looking at the nuts, they could best be described as rust colored clay blobs....they didn't look like nuts any longer.

Grinding off the nut ends (you can see them in the pictures) flush with the flange worked nicely. After they were ground off and in some cases finished off with a cold chisel, I just tapped the bolt out through the other side.
I actually had to grind off some of the shield attaching nuts/bolts as well.

After tightening the nuts and bolts and re-installing the O2 sensor, I started the car up....no warnings or problems, if anyone is wondering about noise levels before/after, honestly, it is barely, barely noticeable.

I thought i'd have to file the flanges flat to get a good seal on the gaskets - no need, it was fine.
I also thought that I'd have to reset the DME by disconnecting the battery and then reconnecting it....I didn't bother and there are no issues so far.

Running this without a muffler and the optional turndown pipe from Fabspeed is ludicrous, unless you hate your neighbors.

Here is the situation before I started




Pictures of the new pipe versus the old, original catalytic converter





I am going to drain the oil and adjust the valves while I have the clearance with the pipe uninstalled, but this is what it looks like without anything there.



If you have any questions or want any pictures, etc., let me know.

Thanks,
Erik.

[mowog63]

Here is the pipe installed

[Fabspeed Motorsport]

Thank you for the write up!
We're glad your enjoying your cat-bypass pipe, even if your neighbors aren't.
Feel free to send us a video clip of how your 911 Sounds with the cat-bypass pipe installed.

[tirwin]

Nice write-up.

Some cars have a O2 sensor reset switch on the back of the tach or the speedo. I can't remember which one off hand. I think it's the speedo because it must be tied to the odometer somehow.

[jjeffries]

What a nice shiny pipe you have! That's a beauty. John

[luyckxglen]

So ur saying no extra sound? what about preformance?

[Jesse16]

Did similar from M&K on my 87. Easy install, about the same loudness at lower RPM's, on the highway definitely more drone but I like. Save you cat, its worth $$. Very difficult to be objective on the butt dyno, others say its worth a few HP.