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STS Turbos: Cat or no cat

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Old 12-31-2005, 02:43 AM
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Default STS Turbos: Cat or no cat

Hi Everyone,

Just wanted to know how many people here with STS systems are running cats versus straight pipes (or have tried both)? I am getting my STS TT installed in my Z06, and the question is if it is worth taking the cats off for possibly marginal horse power gain, versus keeping them on for smog and noise reduction, but have the risk of dislodged cat materials thrown into the turbos. Any comments?

Lewis
Old 12-31-2005, 03:21 AM
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I have done both... you have to remove the cats if you want to use a 2-Step. When removed them it got louder than I care for. If I didnt have a two step I would have left them on.
Old 12-31-2005, 03:25 AM
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I just put LT headers on today. I will let you know next week.
Old 12-31-2005, 03:48 AM
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I say take them out.
Old 12-31-2005, 04:54 AM
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You will have more exhaust velocity without the cats, for better spooling turbos. Bob
Old 12-31-2005, 07:13 AM
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Take them off i agree with bob
Old 12-31-2005, 09:53 AM
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I agree with removing them, but it will be significantly louder. I'm planning on adding a muffler post turbo to quiet it back down.
Old 12-31-2005, 11:48 AM
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I didn't really notice any difference on spool up / performance with cat vs no cat, what I did notice was it is wayyyyyyyyyyy louder without the cats. Leave them on.
Old 12-31-2005, 02:08 PM
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My STS destroyed my cats. No sooner than 24 hours after installing the STS, the cats started to disintegrate and plug up the turbine. Obviously, mine are now gutted, but it still gives the appearance that they're still on. I did pick up another 30rwhp on the dyno without them, but as others have stated, it is much louder. I vote for taking them off unless you live in an emissions-friendly region.
Old 12-31-2005, 03:29 PM
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Rotweiler, did you really lose your cats withing one day?!? How much damage to the turbo?

Heath, as you know, the noise level can be an issue, as we discussed several weeks ago. I think we are going to try both and test it out in person. Ideally we plan to run without cats to minimze the risk of damage from burnt up cat materials. Perhaps we will weld some resonators in place of the cats. What do you think? Interesting that you did not notice much performance change.

Thanks everyone for the insightful comments. Keep them coming!

Lewis
Old 12-31-2005, 04:00 PM
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No lie. I just got the car back and was taking it to a car show the next day. When I got on it, I noticed that it wasnt making any power. The cats had literally come apart and there were pieces lodged in between the blades. Got the obvious pieces out and then swung it by my performance shop on the way home and got the rest of it cleaned out and gutted. Luckily, there wasnt any damage to the turbo at all. More of a PITA than a problem.
Old 12-31-2005, 04:01 PM
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That is the first I have head of a Cat comming apart... I dont think it was due to the STS. If you have an M6 and want a good launch... you need a 2-Step. You MUST remove your Cats with a two step.
Old 12-31-2005, 04:41 PM
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those cats didn't come apart just due to the turbo. they had to have been damaged before or your tune was so far off you toasted them.

lewis - you will definetly get max performance and least worry about damaging the turbo by removing them. putting resonators in their place would be wise to keep the noise down. for me I don't want to worry about emmissions or noise so the cats stay.



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