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American Iron Horse
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406 Posts
Discussion Starter #1
I was thinking about cut outs. The only reason I'd consider getting a cut out is for my girlfriend. That way should could have a quiet ride. Then when I driving it, I could free the beast. My question is what are the pros and cons to cut outs. Here's a website from a LS1GTO sponser that claims 7 more horsepower just by adding on the cut outs. Thoughts/Comments?

http://www.mascperformance.com/catalog/product_info.php?cPath=24_33&products_id=30
 

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13 year owner
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16,379 Posts
Cutouts are a great idea if you don't want to spend all the extra $$$ on a full cat-back system or other exhaust components. When open, the HP gain would be virtually the same as a good cat-back. You may lose some torque though.

I would look into a Quick Time or other electronic cutout as it'll save you from having to crawl under the car each time you want to uncap it. You can set it up to open at the flick of a switch or open at a certain percentage of throttle.

However, they (the auto opening versions) can run into reliability problems because of the temps of the components actuating mechanism. But compared to a good-cat back, you can probably get away replacing 4 or 5 cutouts for the price of one cat-back system.
 

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American Iron Horse
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406 Posts
Discussion Starter #3
Thanks for the reply CMNTMXR57.
 

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American Iron Horse
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406 Posts
Discussion Starter #4
Which cat-back system would you recommend for the 2004 GTO CMNTMXR57? And if you could please provide a website so I can research it. Thanks!
 

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Yes, it has a car seat
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1,884 Posts
My plan is at 36,001 miles (give or take) to pull the manifolds and exhaust and put a whole new system on. By then I figure we should know what's good and what isn't. Now, if only I could solve the internal struggle of cats or no cats...
 

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I say no cats and a some 02 simulators if you are just looking for more power. But be careful because removing the cats can sometimes make your exhaust sound different.
 

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13 year owner
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16,379 Posts
Unfortunately there isn’t cat-back systems (that I’ve seen yet) available for our car. You may want to ask some of the Monaro guys what they’re running. Few the first few months to a year after this car hits the street it may be more of an “experimental” period where you may have to come up with your own setup with a local exhaust shop. I know I’ll probably be spending quite a bit of time with the guys at FLP custom fitting my own setup initially.

The problem with running without cats on an LS1 is that it has a real raspy/poppy sound to it. I don’t care for it. But that subjective to each person. There really is minimal gain to be had running catless vs. a high flow cat (such as a Random Tech unit) and in actuality you may lose some torque to gain 1-2 additional HP. Then there is emissions testing. With the new OBDII scan, with O2 simms you will pass, but if they do a visual, you can quickly get caught, they do have under car mirrors you know. Is that worth gaining a couple HP?

What I may do, is using FLP’s quick connect system is create flanges at each end of a high flow cat that will meet up with the rest of the exhaust plumbing. I will also fabricate straight out “off-road pipes” with flanges on each end that I can run all the time with O2 Simms. Then come emissions testing time, quick swap out the off-road pipe for the cats, pop them in, take the test, pass, come home and switch back to my off-road pipes. I wanted to do this on my Camaro, but my piping is 3.5” all the way and FLP’s max is 3” I think.
 

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Yes, it has a car seat
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1,884 Posts
MI doesn't have emissions bribery, er testing anymore. The only issue I would have is cost. If I can buy a catless system for a lot less than a high-flow cat and get a 1-2 hp gain - why put the cat(s) in? If there is no aftermarket catless system w/o going custom - then the cost is probably not an issue and go high-flow cat.
 

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Hey want are cut outs??

:drink: :drink:
 

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13 year owner
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Tails, it is a pipe that is fit into the exhaust system usually after the cats (if there) that routes the exhaust right out of the system and out into the atomosphere. It doesn't go through the rest of the exhaust into the muffler and out the tailpipes if you have it open.

Here is a picture
 

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Hmm That shouldn't affect the sound then when closed and give you a little hp boost when open. I suppose they are not strictly street legal.
:drink: :drink:
 

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13 year owner
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Anything that raises the sound level above 80 decibels (I think is the regulation) is illegal and technically speaking, tampering with your exhaust to install "performance" parts instead of replacement OEM parts is illegal.

But that doesn't stop anyone.

When closed it's just like a regular system.
 

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American Iron Horse
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406 Posts
Discussion Starter #13
Hey CMNTMX

Have you looked under your GTO to see if a good cut-out system would work?
 

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DY is the Awesomest
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59 Posts
i think that i am going to want a louder exhaust, when i started one up awhile ago, i didn't like how quiet it was, compared to my bf's ws6. But, he is saying to cut the cats, except i WANT to pass the emissions test, unlike him, he doesn't care about that. How can I make it significantly louder (more of a deeper sound) without failing the emissions?
 

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13 year owner
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iron_horse31 said:
Hey CMNTMX

Have you looked under your GTO to see if a good cut-out system would work?
For the brief time I've been under them, no. IN order to be before the mufflers, you'll need to install them under the passenger compartment. That could lead to too much resonance in the passenger compartment.
 

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Captain Thread Killer returns
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I really want to get the Quicktime cutouts.....Are there any problems that might arise from having these on the car? I read a few threads where people mention they could cause a ses code.
 

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Resident 10-second Priest
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Dbluegoat said:
I really want to get the Quicktime cutouts.....Are there any problems that might arise from having these on the car? I read a few threads where people mention they could cause a ses code.
I ordered the QTPs for my 2.5" custom setup. Mainly just for the fun factor. Only problem is, they don't fit. The valve itself is less than 2.5", so I need to go one size up. Also, you'll need to fabricate a custom Y-tube. The Flowtech that QTP sells doesn't fit the Goat.

I'm on vacation now and haven't been able to get it set up, but talk to Barry at QTP. He's been helpful thus far and I know he wants us Goat owners to find a setup that works.

Padre
 

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Captain Thread Killer returns
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PadreGTO said:
I ordered the QTPs for my 2.5" custom setup. Mainly just for the fun factor. Only problem is, they don't fit. The valve itself is less than 2.5", so I need to go one size up. Also, you'll need to fabricate a custom Y-tube. The Flowtech that QTP sells doesn't fit the Goat.

I'm on vacation now and haven't been able to get it set up, but talk to Barry at QTP. He's been helpful thus far and I know he wants us Goat owners to find a setup that works.

Padre
Hey Padre any more on this?
thanks
 

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Resident 10-second Priest
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Dbluegoat said:
Hey Padre any more on this?
thanks
Still working on it. But hopefully by the end of the month when I do my "Stage 2" :secret: :) .

I'll post sound clips and all. Barry at QTP is great to work with. :cool: We'll get it done and I'll let all of you know.

Padre
 
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