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Discussion Starter #1
I just installed my Solo Catless Downpipe on my Solstice GXP with GM Stage 1, and needless to say, I am not impressed with the performance.

For the record, the piece is a quality 2.5 inch pipe and there are no leaks or problems with it. Everything bolted up fine and works well as intended. Great quality.

This catless downpipe exhaust piece installed on Cobalt SS Turbo's has a big difference in power and feel. It also has the LNF. And with my brothers 09 Cobalt SS Turbo with GM stage 1 and catless, it definitely feels a lot more powerful with the new exhaust than without. Same goes for my cousins 10 Cobalt SS Turbo with Trifecta tune and catless, feeling a lot more powerful with the new exhaust than without.

Maybe it is because their systems are a true 3 inch downpipe to catback and ours are a 2 inch reducer where the catback bolts up. I am not sure. But the car literally just sounds like its a bit louder than actually more powerful.

At this point, I am debating on putting the stock downpipe back on because I am this unimpressed with its performance.

Could a few of you chime in here if you know what the power gains are suppose to be with this catless downpipe with stock catback exhaust? I would like to hear what others have to say about this. Honestly, this is kind of depressing. :(
 

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Discussion Starter #3
The rear O2 sensor does not affect the cars performance in any way whether the CEL goes on or not.
 

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The rear O2 sensor does not affect the cars performance in any way whether the CEL goes on or not.
I disagree with this statement. I just had mine go out and had to have it replaced.... The car ran like absolute doodie!!

As far as the Solo cat.... Are you running a straight pipe from Solo, or is it a HFC? If so, this is going to be a "stopping" point. You said you still have the stock exhaust? Your stock exhaust does come down to a 2" pipe... I believe the Solo AM exhaust has 2.5" or 3.0", guess I need to look at mine because I can't remember. With your restrictive OEM exhaust, you won't see the power gains that an AM exhaust can provide for a HFC or straight pipe. Thus the reason I was trying to persuade you to go with the exhaust first.

I personally don't like the GMPP tune as I feel it doesn't bring out the full potential "safe" performance..... Just my $0.02
 

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I wouldn't expect to see much gain (much less seat-of-the-pants gain) from simply a cat delete pipe without a tuning change. I have one on both our Sol and the Cobalt and each requires a tuning change to exploit.
 

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The rear O2 sensor does not affect the cars performance in any way whether the CEL goes on or not.
The rear O2 sensor will ask the ECM for a leaner A/F ratio. Double stacked 18 mm spark plug anti fowlers for the sensor should fool it. A new tune also like others have said.
 

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I just installed my Solo Catless Downpipe on my Solstice GXP with GM Stage 1, and needless to say, I am not impressed with the performance.
You're forgetting that the ecm controls the power output, you can add as many mods as you like and it won't change anything until you make some changes in the ecm.
 

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Discussion Starter #9
I disagree with this statement. I just had mine go out and had to have it replaced.... The car ran like absolute doodie!!

As far as the Solo cat.... Are you running a straight pipe from Solo, or is it a HFC? If so, this is going to be a "stopping" point. You said you still have the stock exhaust? Your stock exhaust does come down to a 2" pipe... I believe the Solo AM exhaust has 2.5" or 3.0", guess I need to look at mine because I can't remember. With your restrictive OEM exhaust, you won't see the power gains that an AM exhaust can provide for a HFC or straight pipe. Thus the reason I was trying to persuade you to go with the exhaust first.

I personally don't like the GMPP tune as I feel it doesn't bring out the full potential "safe" performance..... Just my $0.02
Ok so the 02 bank 1 sensor that is connected to the downpipe is very important and has a direct impact on the performance. The O2 banks 2 sensor that is connected to the downpipe should throw a code indicating that the catalytic converter has gone bad, but, should not effect any engine parameters regarding performance. I thought I should clarify.

The catback exhaust makes sense. Like I said before, my friend with a Saturn Sky Redline with the GMPP tune and a ZZP catless downpipe had more "seat of the pants" gains than from my car.

An aftermarket tune is something I am considering but not until next year.

Does your car have a tune or is it otherwise stock? If you do not have a tune the ECM will learn down any performance gains
GMPP Stage 1 kit.

I wouldn't expect to see much gain (much less seat-of-the-pants gain) from simply a cat delete pipe without a tuning change. I have one on both our Sol and the Cobalt and each requires a tuning change to exploit.
Interesting. Yes an aftermarket tune shows more potential than what the GMPP tune does but for right now, it just seems to me that it did a lot more on the other 3 cars I mentioned earlier.

The rear O2 sensor will ask the ECM for a leaner A/F ratio. Double stacked 18 mm spark plug anti fowlers for the sensor should fool it. A new tune also like others have said.
I will most likely just try this anyway. I am considering ordering ZZP's kit.
 

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I'd get all the peices to the puzzle before talking down on a company's product. You can't expect much gain from a performance part without adjusting the car to the changes.
 

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Discussion Starter #11
I'd get all the peices to the puzzle before talking down on a company's product. You can't expect much gain from a performance part without adjusting the car to the changes.
I was not talking down on the company's product. I said earlier that the product was fantastic as a piece. It was quality fit and finish.

I am referring to ALL catless downpipes when I speak about my complaints.
 

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The O2 banks 2 sensor that is connected to the downpipe should throw a code indicating that the catalytic converter has gone bad, but, should not effect any engine parameters regarding performance.
I can tell you for sure that IT DOES affect engine parameters. I JUST went through this 2 weeks ago with the #2 sensor. As a matter of fact, during the cat warm-up phase, my BOV was opening and closing causing surging of the turbo and the psssshhhh noise several times during warmup. Furthermore, the car had zero performance. If I would get on it at all, the car studdard and felt like it was missing.... It actually felt like my clutch was slipping. So it does affect engine parameters!!!!
 

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Guys,
He came in with some techincal questions, lets do what we can to help him out. :grouphug:

If I am reading your post correctly, you have the GMPP Stage 2 kit installed which will allow the ECM to take advantage of the potential improvement provided by some hardware additions.

Over the course of several years of reading inputs on this and the Sky forum, my understanding is that a high flow cat in conjunction with a tune that supports "learning up" will add 14 to 18 WHP when measured before and after on a dyno.

I have not seen meausred numbers for a cat delete, but if the above is true and its a result of increased exhaust flow then one would think that going totally catless would provide at least the same improvement and potentially more than the 18 WHP improvement.

The platform engineers stated catagorically that the stock exhaust, with the exception of the cat, did not inhibit HP production until you get well above the power levels that a "safe" tune will provide. All the data I have seen suggests that nothing you do from the cat back has any significant measurable improvement in power output.

Since you stated that you have the GMPP tune, and assuming that your configuration is working well and has no problems, then the next question is how many key cycles have you executed? It appears that the ECM needs about 6 key cycles to fully "learn up" to the potential of a significant hardware upgrade like the cat delete. I personally observed increased boost and performance over 6-7 cycles when I put the high flow cat on my car.

Just for clarity, any "canned" tune should allow you to see a significant improvement in HP with the addition of the cat delete pipe. If you are not seeing the improvement, then it may be time to do some checking. Are your cam servos / cam position sensors working as designed? There have been instances where one or more have failed and the car just keeps on running but not producing as much power.

Have you run the car on the dyno to get a baseline?

My GXP with all the hardware add ons was measured by Doctor Dave at 305 WHP with a high flow cat installed. Theoretically it would have been marginally higher with the cat delete.
 

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I can tell you for sure that IT DOES affect engine parameters. I JUST went through this 2 weeks ago with the #2 sensor. As a matter of fact, during the cat warm-up phase, my BOV was opening and closing causing surging of the turbo and the psssshhhh noise several times during warmup. Furthermore, the car had zero performance. If I would get on it at all, the car studdard and felt like it was missing.... It actually felt like my clutch was slipping. So it does affect engine parameters!!!!
Very Interesting: I have had an intermittent "Cold Start Cough" for a couple years, that I have never been able to completely track down. No other noticeable performance issues. But every now and then, during the CAT warm up cycle: The car will "Cough" and when it does the boost gauge will indicate a blip of 1-2 PSI and occasionally I will hear the BOV open.

One of these days, I will just change the downstream O2 sensor and see if the problem goes away.
 

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You are correct Rob...and I apologize if I was out of line. Especially after I called a few of you out on it last year...LOL. I was just trying to get my point across about the #2 O2 sensor.
 

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Discussion Starter #16
I can tell you for sure that IT DOES affect engine parameters. I JUST went through this 2 weeks ago with the #2 sensor. As a matter of fact, during the cat warm-up phase, my BOV was opening and closing causing surging of the turbo and the psssshhhh noise several times during warmup. Furthermore, the car had zero performance. If I would get on it at all, the car studdard and felt like it was missing.... It actually felt like my clutch was slipping. So it does affect engine parameters!!!!
Well so what did you end up doing to resolve this issue?

Guys,
He came in with some techincal questions, lets do what we can to help him out. :grouphug:

If I am reading your post correctly, you have the GMPP Stage 2 kit installed which will allow the ECM to take advantage of the potential improvement provided by some hardware additions.

Over the course of several years of reading inputs on this and the Sky forum, my understanding is that a high flow cat in conjunction with a tune that supports "learning up" will add 14 to 18 WHP when measured before and after on a dyno.

I have not seen meausred numbers for a cat delete, but if the above is true and its a result of increased exhaust flow then one would think that going totally catless would provide at least the same improvement and potentially more than the 18 WHP improvement.

The platform engineers stated catagorically that the stock exhaust, with the exception of the cat, did not inhibit HP production until you get well above the power levels that a "safe" tune will provide. All the data I have seen suggests that nothing you do from the cat back has any significant measurable improvement in power output.

Since you stated that you have the GMPP tune, and assuming that your configuration is working well and has no problems, then the next question is how many key cycles have you executed? It appears that the ECM needs about 6 key cycles to fully "learn up" to the potential of a significant hardware upgrade like the cat delete. I personally observed increased boost and performance over 6-7 cycles when I put the high flow cat on my car.

Just for clarity, any "canned" tune should allow you to see a significant improvement in HP with the addition of the cat delete pipe. If you are not seeing the improvement, then it may be time to do some checking. Are your cam servos / cam position sensors working as designed? There have been instances where one or more have failed and the car just keeps on running but not producing as much power.

Have you run the car on the dyno to get a baseline?

My GXP with all the hardware add ons was measured by Doctor Dave at 305 WHP with a high flow cat installed. Theoretically it would have been marginally higher with the cat delete.
No I didn't get the car on the dyno for a baseline.

I actually called Solo today about their O2 bung extender and they told me that the one they offer won't work eliminating the CEL.
 

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I had to have the O2 sensor replaced. Mine is a long story (see my WP thread). I'll give you the short version. I took my car in for a waterpump replacement. Rather then do the repair the way the GM procedures manual says, they took my cat off to get at it. Well, I had a Solo HFC, and they had to cut it off....then replaced it with an OEM cat. I have had issues with a CEL ever since they did this... Until it finally gave up the ghost and went bad. I had it replaced about 2 weeks ago. And now that the OEM cat is on it, they just replaced it with an OEM O2 sensor. Car runs fine other then I can feel and definetly hear the difference. I will be orrdering a new Solo one this fall!! ;)

Hey Rotary, PM me as to where you live...I'm in Waterford.
 

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Discussion Starter #18
I had to have the O2 sensor replaced. Mine is a long story (see my WP thread). I'll give you the short version. I took my car in for a waterpump replacement. Rather then do the repair the way the GM procedures manual says, they took my cat off to get at it. Well, I had a Solo HFC, and they had to cut it off....then replaced it with an OEM cat. I have had issues with a CEL ever since they did this... Until it finally gave up the ghost and went bad. I had it replaced about 2 weeks ago. And now that the OEM cat is on it, they just replaced it with an OEM O2 sensor. Car runs fine other then I can feel and definetly hear the difference. I will be orrdering a new Solo one this fall!! ;)

Hey Rotary, PM me as to where you live...I'm in Waterford.
Ahh so you never had a Catless before then.

I am thinking of buying one of these 2 products below to try and fix that.

Vibrant Performance ::.

ZZPerformance - 02 Bung Extender #ZZ-O2BE

Thoughts? Input?
 

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You are correct Rob...and I apologize if I was out of line. Especially after I called a few of you out on it last year...LOL. I was just trying to get my point across about the #2 O2 sensor.
All is good. No crossing of lines here. Just wanted to focus on getting the answers if we had any to contribute. And I was personally a little confused and had to read the inputs a couple of times before I figured out what his baseline configuration was . .. is.:thumbs::thumbs::thumbs:
 
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