Also, you may get CEL and need to turn it off via Durametric software.

 

Other than CELs which you should get a flash for cat bypass anyway, you will notice more emission fumes when parking indoors or standing outside while idling, or for those driving behind you. This is what causes the visible soot stains on the rear bumper etc.

Others with cat bypass please chime in if you experience any odor or fumes...

 

Uh, just so you know, removing or tampering with an emission control device is a violation of federal law. The 1988 Clean Air Act forbids BOTH individuals or dealers from doing anything to defeat an emission control device.
Dealer are forbidden to work on such vehicles until they are restored to "normal" condition.
It is also illegal in many states to sell any such modified vehicle, or trade it in.
The penalties are severe, $25,000 per occurrence.
If a dealer is caught, the EPA will audit records going back 7 years to determine the extent of the crimes.

Sorry to throw cold water on your fun, but this is a serious federal offense.

For racing, you can do what you want, but the car must be trailered to and from the race track.

 

thanks for the info president Obama. This is something new that I was not aware of.

Nowhere in my post did I state that my car is my DD nor my track car.

 

A few years back, the automotive aftermarket started selling "catalytic converter test pipes". These were straight pipes that were an exact replacement for the cats so you could "make sure your cats weren't clogged". They were clearly marked "not for highway use".
The market sold tens of thousands of them until the Feds caught wind of it.
They issued subpoenas to every step in the distribution chain down to the consumer level. People went to jail and paid millions in fines.

Think the Feds don't read 6Speed?

I served on the SEMA Board of Directors for a few years and saw first hand what can happen. Just be careful and make informed decisions.

 

I think we are assuming the Feds can read. Most could not even find the cats on our cars.

 

I have a catless FVD that i only use off-road in my driveway(lol)

The downsides are:
1)A small smell when windows are down and you're stopped/reversing


Upsides are:
1)More Power
2)Better exhaust sound
3) Car will shoot small flames when you let go of gas at a high RPM and you will have several explosion type sounds from backfires happening due to no cats to catch the extra fumes

 

Here is my thoughts.

1. It sounds GREAT!!!
2. Quicker Spool and more power.
3. The smell of the fumes are terrible. It's a dead giveaway for law enforcement. (gotta be real
careful)
4. No CEL issues so far.

You will like your CG exhaust Nico. They sound great.

 

I have AWE Gen 2 exhaust and put on cat-delete pipes (for the track).
As far as the cat-delete goes, surprisingly there's less "thunder" from the AWE exhaust. But you definitely hear a LOT more whirring and hissing from the turbos. Pedestrians must think there is an angry snake coming at them. I'm not sure if I love it yet but I'll give it some time. There's also a bit of "whine" with light throttle and I'm not sure why that is. It was with the window down and light throttle acceleration. It sounds like a racing car sound. Sorry I can't describe it better. Just got it so I'll post more impressions later...

 

I only smell it when the car is at a stop with engine running, otherwise I smell nothing.

 

Yep, it's pretty strict in CA. Technically, anyone with an aftermarket exhaust and catalytic converter that is not on the approved CARB list is in violation of the law which means that's everyone on this board who lives in CA whether you have a cat or not. So we're all off-roading....

 

sorry to bring this thread back up

On a Remapped/Tuned 997.1 TT with a possible DMS/Miltek Sports Exhaust that currently has the HJS 200 Cell Cats would there be any benefit with removing the HJS cats and just having a straight pipe from the turbo to the Mufflers/Backbox?

Basically de-catting the current sports exhaust?

Noise is not the concern at the moment

Just want to know realistically how much more power is there to be had?

If its only like 20 bhp more its not really worth the aggro removing the cats as i don't think you'll feel those extra small ponies?

Could someone please educate me with proven data

thanks

 

Other future mods will be 65mm Modded VTG's

Don't really believe in bhp figures am more into the fact is how de-catting, other mods etc actually perform in the real world where it matters rather then pub talk figures

 

I had a exhaust with 100 cells cats and now i have a decat system. The egt's dropped quite a bit which allows to have a more agressive ecu tune. Just by that is worth it.

 

A 200 cell cat has a life expectancy of about 20,000 miles - less if the car is tracked. Mine lasted about 15,000 miles. A bad cat will increase exhaust gas temps and back pressure which will have the ECU pulling boost, timing, etc. in an attempt to compensate. Under normal driving conditions this might not even be noticeable but on the track or under extreme driving conditions it will create havoc and a fouled cat is not at the top of most peoples diagnostic troubleshooting list. If you go catless, you rid your car of a significant heat source and heat is a major contributor to all sorts of problems.