991.2 Cat Bypass owners
 

Lots of decent info out there about replacing stock PSE cats with high flow Sport Cats from various manufacturers.
Definitely seems like a solid way to give a performance boost and change the exhaust note.

Not so much about the Cat-Bypass systems alone, which definitely seem to be a cheaper, but more aggressive option than the High-Flow Sport Cat setup.
Fabspeed, Soul Performance are just a few examples.

Thats what I am currently interested in hearing about.
There are a few videos online. But we all know those videos can be hard to translate into real world use.

I'd love to hear real-life experiences from those who had cat-bypass systems installed on their 991.2.
Aside from the obvious.....its some degree louder, and can have a more distinct exhaust smell.

What are the real life negatives from those who had them installed? Positives over the Sport-Cats?
I know there is likely a higher chance of CELs. But just how frequent were these issues happening? Were they game changers? What did people do to fix them?
Are they legit too loud or aggressive for daily driving? Is that a ridiculous idea?

For reference, I'm daily driving a '17 GTS MT.
Looking to keep stock muffler and stock headers for the time being.



Cheers,
W

Whacky,

Thanks for the shoutout :D There are several options available on the market as you mentioned and I do not wish to create a shameless plug with this post, but hopefully I can shed some light on your question while we wait for the user base to chime in. If daily driving I would recommend the Sport Cat option over the Catbypass pipes. Reasoning for that is threefold, first the likelihood of getting a CEL with Catbypass is higher (it's almost a guarantee unless you run O2 Spacers or a tune, and some dealers may put up a fuss), secondly on a daily driver the smell can sometimes be just a bit much (this is very suggestive to say the least, some say it's not big deal and others will say it smells like a gas chamber) and lastly, to get the true benefit of Catbypass I would really recommend a custom tune to go with it.

A custom tune will not only turn off the check engine light, but it will absolutely gain a significant improvement in performance that compliments the Catbypass pipes perfectly. IMO if you are not interested in getting a custom tune, the Sport Cats are the perfect balance between sound, performance, smell and warranty compliance that will get you 80% of the sound and performance of the Catbypass without the check engine light, smell or need for a tune (though it would still benefit of course).

You should find a significant pool of owners here who have had some experience with this, Rennlist is great for that. Of course you can give me a shout any time if you have more questions.

Best,

Evan

These are as accurate sound clips Ive heard to what they sound like in real life

Every car Ive smelled with cat bypass sounds better but smells terrible. I would spend the extra and go with sport cats because of the smell. They still get 95% of the flow of a full cat delete, which is usually waaay better than stock. My 2c.

I had my dealer install catbypass immediately after my car arrived from port and made it to the dealer.
I was able to put 1000 miles before I had to winterize my ride.

I didn't have an issue with smell but when you get out and walk around back, you can smell a difference.

IMO, besides the tremendous sound increase, the best part of bypass pipes is the throaty sound and amazing burbles compared to stock or sport cats.
They made it sound like they were coming from a V-8 IMO.
The downside is that my wife hated the sound, especially cold starts.
Basically, she was embarrassed to be near the car at start up.

Since then, I ordered Sport Cats and installed them one morning a few weeks back.
I was motivated to do this cause the temps made it up around 50/55 degrees here in Michigan.
I took the car out for 150 miles over the course of the weekend to try and get a feel for the swap.

My wife could tell the sound was a touch quieter and so could I.
The burbles were a little softer (than bypass pipes) but certainly better than stock.
I've told others that pm'd me, if I were single, I would be tempted to put the bypass pipes back on.

Who knows, I just don't have enough run time with the Sport Cats yet.
That being said, due to the strong opinion of the wife.....the bypass pipes are listed for sale here in Rennlist classified ad if anyones interested.

https://rennlist.com/forums/parts-ma...se-system.html

Did you ever get CEL with these or did the o2 sensor help with that?

Rear engine makes all the difference in the world not having to smell anything while driving.

Strange, considering the fact that the smell of un-treated tailpipe output is the source of the smell, and front engine cars generally have tailpipe that exit in roughly the same location. Not sure if this was an attempt at humor.

Can you please share a sound clip of the Sport Cats?

thank you @flickroll.
i'm really wondering what the diff is between the cat delete and the sport cats would sound, and what the diff is between Fabspeed and Soul PP on the same product.
I had an Akro on my race bike for many years, changed it to SC Project last year and the sound and performance have drastically changed it for me. While my fellow riders don't agree, i found that the sound and response in the turns made a huge diff.
Hard decision ahead, but who is complaining ;)

Yeah I really don't want to deal with the hassle of the CELs and having to get them reset.
Not sure how often those would happen with O2 spacers installed.

I really, really want to like the cat bypass system.
But its slowly looking like the Sport-Cat option is making more sense for a daily driver that is going to get some real miles put on it.

I received 2 CEL's w/ bypass pipes and O2 spacers over the course of 1000 miles. However, both went away on their own after about 5 restarts of car.
I did NOT have to go into dealership to reset. When I told my Porsche Service Manager that, he was surprised the car would 'reset' itself.

Not at all. In every front engine car the small was always significant. When I had Soul Race headers on my 991 there was no smell from in the car while driving. There was no exhaust leaks so I don't know the scientific reason.... I just know what I smelled.