[AJL_SS]

Hey guys, I see a lot of people deleting the secondary cats but I assume much of that is for noise as the primary cats is where the restriction is at. Has anyone installed the CA Cat Deletes? If so how do you like the sound and if anyone has dynoed and seen gains please share if you don't mind. Thanks guys!

[JFM-jr]

Just a FYI you will need to tune the car to avoid Check Engine Lights as well as make alterations to the ECU as some here have noticed the knock sensors pick up additional activity from the cats being removed and timing can be pulled.

[AJL_SS]

Yea im planning on ordering th DMS Flex Fuel kit and then tuning the car on E85 but wanted to know if these cat deletes did anything to install them before I tuned. Thanks for the heads up though!

[EFI Tuning]

I have the CA deletes on my vehicle. I installed them more for easy wideband access more than anything. There is a little bit of power to be gained at the top end but nothing earth shattering. From 6000-6500 RPM there was a 5-7 RWHP gain (stock tune). The car does get louder without the primaries. The secondary cats may be holding things back a bit. If I wasn't going to install headers soon I would test it out.

The knock sensors absolutely needed attention on my vehicle. A resonance gets created in certain RPM spots on certain cylinders that excite the knock sensors significantly. It is completely addressable.

If you are interested I can supply a completed tune for E85/CA delete and the E85 kit itself.

Please let me know if you have any questions!
Tim

[JFM-jr]

Originally Posted by EFI Tuning

I have the CA deletes on my vehicle. I installed them more for easy wideband access more than anything. There is a little bit of power to be gained at the top end but nothing earth shattering. From 6000-6500 RPM there was a 5-7 RWHP gain (stock tune). The car does get louder without the primaries. The secondary cats may be holding things back a bit. If I wasn't going to install headers soon I would test it out.

The knock sensors absolutely needed attention on my vehicle. A resonance gets created in certain RPM spots on certain cylinders that excite the knock sensors significantly. It is completely addressable.

If you are interested I can supply a completed tune for E85/CA delete and the E85 kit itself.

Please let me know if you have any questions!
Tim

To the OP in case you are not aware THIS is a guy to pay attention too. Been in the game a long time very knowledgeable and offers help to this forum frequently. A solid asset to this forum.

[oldman]

I did not get any knock Retard on my M6. Initially the system was too tight on the drivers side and I left the clamp loose. After 2 months or so I tighten it up.

I'm going to LTubes and off road pipes. I've been tossing the idea around of putting a least one stainless flexpipe in the system to reduce resonance / vibration. Probably should.

[EFI Tuning]

Originally Posted by oldman

I did not get any knock Retard on my M6. Initially the system was too tight on the drivers side and I left the clamp loose. After 2 months or so I tighten it up.

I'm going to LTubes and off road pipes. I've been tossing the idea around of putting a least one stainless flexpipe in the system to reduce resonance / vibration. Probably should.

It's very specific RPM bands that do it on my car. No matter how much timing I pulled it didn't change. E85 didn't phase it.

Tim

[TJay74]

Originally Posted by JFM-jr

Just a FYI you will need to tune the car to avoid Check Engine Lights as well as make alterations to the ECU as some here have noticed the knock sensors pick up additional activity from the cats being removed and timing can be pulled.

Sorry, but this info is not accurate. The secondary cat unless GM has changed how they put them on vehicles since I got my 2016 truck are after the post cat O2 sensors.

You can remove the secondary cat and will not need any tuning in regards to codes or anything else.

GM used to build 2 versions of each vehicle, a 49 state vehicle and a CA only vehicle. Several years ago as a cost cutting measure they dropped the 2 separate lines and moved to a 50 state vehicle, in order to do that they had to add the secondary cat to all vehicles.

The primary cats have the front O2 which monitor the actual fueling changes and allow the ECM to change the fueling trims, the rear or post cat O2 sensors only tell the ECM if the catalyst process is working or not, they impart no data at all in regards to fueling changes.

I will be removing the secondary cats on my Camaro once I get it, I have done it before with no issues.

[AndyUK]

Originally Posted by TJay74

Sorry, but this info is not accurate. The secondary cat unless GM has changed how they put them on vehicles since I got my 2016 truck are after the post cat O2 sensors.

You can remove the secondary cat and will not need any tuning in regards to codes or anything else.

GM used to build 2 versions of each vehicle, a 49 state vehicle and a CA only vehicle. Several years ago as a cost cutting measure they dropped the 2 separate lines and moved to a 50 state vehicle, in order to do that they had to add the secondary cat to all vehicles.

The primary cats have the front O2 which monitor the actual fueling changes and allow the ECM to change the fueling trims, the rear or post cat O2 sensors only tell the ECM if the catalyst process is working or not, they impart no data at all in regards to fueling changes.

I will be removing the secondary cats on my Camaro once I get it, I have done it before with no issues.

The CA test pipes the OP is referencing remove the primary cats, they will need a tune.

[TJay74]

Sorry, guessed I missed that part. Then yes, removing the primary cats will require the rear O2 sensor codes to be tuned out.

[RuthleSSchevy]

If my bung is inches before the long tubes collector flange and i want to be able to run both open headers and full exhaust with green cats/mufflers what type of tune is required. From what i understand for proper trim and idle 2 seperate tunes will be needed. Tuners, Any advice?

[EFI Tuning]

Originally Posted by RuthleSSchevy

If my bung is inches before the long tubes collector flange and i want to be able to run both open headers and full exhaust with green cats/mufflers what type of tune is required. From what i understand for proper trim and idle 2 seperate tunes will be needed. Tuners, Any advice?

ECM logs would really be needed to see if two separate calibrations are needed in that scenario. The open headers may or may not need additional changes. It's difficult to speculate. The rear O2s you could leave disabled full time from a calibration perspective if you find you don't need two separate calibrations.

[RuthleSSchevy]

Thanks EFI, yes i am still kicking myself for not recording the ecm logs when i tried this with the stock tune, manifolds for comparison. Using exhaust diverters . Dident work so i welded the pipe back in the moved diverters back to mufflers temporarily. Just until i get the long tubes installed this winter.

[EFI Tuning]

Originally Posted by RuthleSSchevy

Thanks EFI, yes i am still kicking myself for not recording the ecm logs when i tried this with the stock tune, manifolds for comparison. Using exhaust diverters . Dident work so i welded the pipe back in the moved diverters back to mufflers temporarily. Just until i get the long tubes installed this winter.

Let me know if I can be of assistance when you get to the LT phase.

Thanks,
Tim