Cat delete ?

Tori · 08-14-2016, 08:53 PM

Is it beneficial to remove the catalytic converter ? Power gain, driveability ? I did a search but didn't come up with any chatter about the topic.

DRACO A5OG · DRACO A5OG's Garage

Whoa a loaded question. If you are in California, it is illegal unless you are testing the car, wink wink or tracking it, wink wink.

It will give you a little more mid to top end but may sacrifice bottom end torque. It will be a little bit louder too, depending on which by-pass you get.

If you want noticible gains get a SW Chip, programed with or without the cat. She will idle better and the dreaded "low speed bucking" in the parking lot will go away. Redline is also pushed out a bit.

Gas mileage will be affected if you also delete the O2S.

Side effects, smell of unburnt fuel.

Others will post their findings after installing their SW Chip +/- cat.

Tori · 08-14-2016, 09:38 PM

Thanks Draco, I forgot about the presence of the O2 being in the cat. If i were to make a "test" pipe for use when hitting the track, i'd install a bung to keep the O2.

I don't want the car to be any louder, so maybe this isn't the best choice.

DRACO A5OG · DRACO A5OG's Garage

Yeah, you can always remove it after track days

Another, little boost is to get a pre-cut air box cover, again it will make her louder when you punch it.

Where are you located? If you are in SoCal, you can listen to my car, I have an OEM Euro Pre-Muffler (fancy test pipe) with O2S bung, Cut Air Box and SW Chip.

A quality test pipe will make the exhaust a bit louder but not unpleasant like when I had the B&B test pipe on it. A quality test pipe or by-pass will be more bass in the tone. I also had the M&K pre-muffler, it is louder than the Euro but was quieter according to my friend that traded with me.

Tori · 08-14-2016, 11:17 PM

So is there more to some of these test pipes ? Do some of them have built in muffler characteristics, or resonators ?

Tori · 08-14-2016, 11:35 PM

Nevermind..... i've found some posts on this very subject...... lots of reading to do.

DRACO A5OG · DRACO A5OG's Garage

B&B is just a straight pipe
M&K has a inner baffle with SS insulation surround ( but that burns off quickly, then goes a little louder )
Fab Speed, ( not sure )
Dansk and OEM Pre-muffler has a inner baffle a 3rd of the way. What I noticed on my OEM Pre-muffler, there is a plate with holes to help keep back pressure for low end torque.

I think Bursh makes one too???

Tori · 08-15-2016, 08:16 AM

That's good info. Thank you. I think i'd like to find an OEM Pre Muff. Best place to look for one ?

jeffbottman · 08-15-2016, 04:25 PM

I've posted this before, but it's a good datapoint. My car:

Cat delete, replaced with M&K premuffler.
M&K 1 in / 1 out sport muffler.
Steve Wong chip for premuffler.

Recent dyno shows 211 rear wheel HP, about 240 crank HP, which is quite a bit above US stock HP. Very smooth HP and torque curves.

It is a bit stinky. But then again it is obnoxiously bright (illegal bulbs) and rather loud as well.

rusnak · 08-15-2016, 04:52 PM

I do a lot of testing with the test pipe. It's all in the name of science.

DRACO A5OG · DRACO A5OG's Garage

Quote:

Originally Posted by rusnak

I do a lot of testing with the test pipe. It's all in the name of science.

.

Yeah, OP, OEM is hard to find these days. If you do you will need to take it to a muffler shop and have them put a bung on it, make sure it is in the correct position.

Good Alternative is the DANSK pre-muffler with O2S bung, next would be the M&K.

HorstP · 08-15-2016, 10:23 PM

The OEM catalytic converter is like putting a cork in the exhaust. I have replaced the original ceramic type cat with a 100cpi metal cat, that made a huge difference, of course with the right chip. The original housing was used, so you can't see a difference from the outside and with a warm motor it passes smog.

Since then I have however moved to headers with 2 metallic cats into a 2 in, 2 center out muffler.

RarlyL8 · RarlyL8's Garage

Here is a picture of our premuffler. Muffler body has the look of a cat. Includes merge collector, 321 stainless, and O2 bung.

theiceman · 08-16-2016, 10:09 AM

I think you have a busted clamp there ..

Cevan · 08-16-2016, 01:09 PM

Quote:

Originally Posted by RarlyL8

Here is a picture of our premuffler. Muffler body has the look of a cat. Includes merge collector, 321 stainless, and O2 bung.

Hey Rarly8, I have your pre muffler and muffler. It only cam with one clamp for the muffler. Your picture shows two. Is a second one needed?

shaunmbenson · shaunmbenson's Garage

I swapped my Cat for an M&K premuffler -- in conjunction with my SW chip it drives like a new car. I A/B'd it with just chip and Cat and it's definitely punchier with the premuffler.

groovydude · 08-16-2016, 02:03 PM

I'm curious if anyone has actually compared a gutted cat with a premuffler ala OEM or Danske? Is there a noticeable difference in the torque, or is it just theory? I'm running a stock muffler and headers.

rusnak · 08-16-2016, 04:47 PM

Quote:

Originally Posted by HorstP

The OEM catalytic converter is like putting a cork in the exhaust. I have replaced the original ceramic type cat with a 100cpi metal cat, that made a huge difference, of course with the right chip. The original housing was used, so you can't see a difference from the outside and with a warm motor it passes smog.

Since then I have however moved to headers with 2 metallic cats into a 2 in, 2 center out muffler.

You have that backwards, Amigo. The aftermarket ones are cheaper ceramic, and they don't last. The OEM ones are big bucks, rare metal, higher flowing cats.

HorstP · 08-16-2016, 05:01 PM

Wrong. I will post pictures of before and after and you will rethink your statement.

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RarlyL8 · RarlyL8's Garage

Only one clamp is needed on the latest version of the single inlet single outlet muffler. We made the inlet adjustable so you don't need two clamps to help give the angle you want, the single clamp will secure the muffler in place. It only weighs about 12 pounds.