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Anyone ever use these? I have a Cobb on order (thanks Sam @By Design). I'm' not planning on changing my exhaust, but in order to run stage 2 I need to at least get rid of the cats.
Ideally, with the cobb stage 2 map, you'd want to be running race cats (100-200 cell), paired with OEM or aftermarket muffler.
That said, you Can run the stage 2 map with these catless downpipes.
Catless DP's should yield ~5-10whp more than race cats.
If/when you get exhaust/o2 sensor codes, you can clear them with the Cobb AP.
I run custom made cat bypass pipes, car runs great, Managed to do 5.9s 60-130 in cool weather using 94octane pump gas. 991.2TTS with glass sunroof and FAL etc.
Thanks Sam for the info, really helpful guy He let me know that the oem muffler isnt so restrictive and tried these pipes. I do have other cars - 996tt with external gates and alpha10+ gtr with full 4"pipes to get the racecar type exhausts.
If you want your car to be quiet enough, this is the way to go. Still, if you are looking for more raw sound, like GT3.. this isn't going to be aggressive enough for you
Stef from Europipe put some numbers recently OEM muffler with test pipes (catless): 0.14 Bar
To put the low back pressure into perspective here is some more data:
OEM muffler with OEM cats: 0.35 Bar
OEM cats with a 65mm straight pipe (no muffler): 0.29 Bar
Ideally, with the cobb stage 2 map, you'd want to be running race cats (100-200 cell), paired with OEM or aftermarket muffler.
That said, you Can run the stage 2 map with these catless downpipes.
Catless DP's should yield ~5-10whp more than race cats.
If/when you get exhaust/o2 sensor codes, you can clear them with the Cobb AP.
So, the Cobb AP can permanently clear a CEL due to the missing cats as it comes from Cobb?
I run custom made cat bypass pipes, car runs great, Managed to do 5.9s 60-130 in cool weather using 94octane pump gas. 991.2TTS with glass sunroof and FAL etc.
Thanks Sam for the info, really helpful guy He let me know that the oem muffler isnt so restrictive and tried these pipes. I do have other cars - 996tt with external gates and alpha10+ gtr with full 4"pipes to get the racecar type exhausts.
If you want your car to be quiet enough, this is the way to go. Still, if you are looking for more raw sound, like GT3.. this isn't going to be aggressive enough for you
Stef from Europipe put some numbers recently OEM muffler with test pipes (catless): 0.14 Bar
To put the low back pressure into perspective here is some more data:
OEM muffler with OEM cats: 0.35 Bar
OEM cats with a 65mm straight pipe (no muffler): 0.29 Bar
So, the Cobb AP can permanently clear a CEL due to the missing cats as it comes from Cobb?
Thanks.
Afraid not.
The CEL/fault code is triggered by running catless.
The Cobb can Temporarily clear the CEL/fault code(s). But for as long as you're running catlless with stock/cobb ots tune, the codes will reappear again and again.
You can erase them again or leave them be.
The way the car drives won't change.
Apart from the CEL/fault code, there's no real harm done.
Granted, you could optimize the tune further for the catless downpipes - to bump up power/effeciency - but there's nothing wrong with you sticking to any of the cobb ots stage 2 maps.
For what it's worth, power wise, my 3" race exhaust paired with equal length tubular headers didn't really yield any power/performance benefit over my previous setup; OEM everything paired with catless downpipes.
If you're after sound, then it's a Very different story.
Afraid not.
The CEL/fault code is triggered by running catless.
The Cobb can Temporarily clear the CEL/fault code(s). But for as long as you're running catlless with stock/cobb ots tune, the codes will reappear again and again.
You can erase them again or leave them be.
The way the car drives won't change.
Apart from the CEL/fault code, there's no real harm done.
Granted, you could optimize the tune further for the catless downpipes - to bump up power/effeciency - but there's nothing wrong with you sticking to any of the cobb ots stage 2 maps.
For what it's worth, power wise, my 3" race exhaust paired with equal length tubular headers didn't really yield any power/performance benefit over my previous setup; OEM everything paired with catless downpipes.
If you're after sound, then it's a Very different story.
good luck
How will the car sound with stock muffler/no cats?
More than volume, the 991tt needs help with tone in my opinion.
Speak to Sam about Kline.
Kine addresses the tt's tone very well. And they have many different volume levels as well.
my pleasure the access port should be waiting for you when you get back and I’ll be here for you if you need some support getting it installed and set up to its full potential! Regarding the bypass bypass it’s a great option for those who are not looking for too much sound or perhaps not quite ready for a full exhaust system. Through extensive testing and independent results we’ve seen between 10 and 20 hp and 20 and 30 pounds of torque gained by running the bypass on the stock exhaust system. This is about 80% of what you get from changing the entire exhaust until you start getting into upgraded turbo chargers and more pressure than we see that if it’s from changing the whole system. It’s a good intermediate option for some as is the sport Cadillacs in place of the original they all have their place and pros/cons.
my pleasure the access port should be waiting for you when you get back and I’ll be here for you if you need some support getting it installed and set up to its full potential! Regarding the bypass bypass it’s a great option for those who are not looking for too much sound or perhaps not quite ready for a full exhaust system. Through extensive testing and independent results we’ve seen between 10 and 20 hp and 20 and 30 pounds of torque gained by running the bypass on the stock exhaust system. This is about 80% of what you get from changing the entire exhaust until you start getting into upgraded turbo chargers and more pressure than we see that if it’s from changing the whole system. It’s a good intermediate option for some as is the sport Cadillacs in place of the original they all have their place and pros/cons.
I’m running straight pipe from turbo back, no cats, no muffler. Car is very loud on cold start. After cold start, in normal mode it is relatively quiet at low speed only when not on throttle or barely touching throttle.
If if I get into boost, in any mode, it gets loud quick.
11-25-2018, 08:46 PM
Cat bypass pipes
He let me know that the oem muffler isnt so restrictive and tried these pipes. I do have other cars - 996tt with external gates and alpha10+ gtr with full 4"pipes to get the racecar type exhausts.
