will no cats hurt performance?
04-25-2013, 11:00 PM
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will no cats hurt performance? i have factory manis and y pipe that came with factory slp dual dual exhaust and a muffler delete. will gutting the cats hurt performance or mpg? and i dont care how loud or annoying or raspy it is... all i give a **** about is performance and mpg. and for that matter did the muffler delete hurt performance at all? will i not have enough back pressure or will it hurt scavenging? also if i gut my cats and put em back in place will i have to weld a pipe inside to not interupt flow? what if i just throw em back on gutted? will that hurt anything? and i dont want to cut them in half and weld em over a ory either. was also thinking of getting a 18" dynomax bullet... would that help with any of the problems? i know its a lot of questions but thanks for any and all help. getting a frost tune soon as well if that makes any difference. also can put my dual dual exhaust back on if it helps performance. thanks 
Last edited by kingof951; 04-25-2013 at 11:18 PM.
04-26-2013, 10:01 AM
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Performance is better without cats. Until 1975 nothing had cats, adding them was always a matter of emissions and had nothing to do with improving performance.
A muffler delete isn't going to hurt horsepower either. This is similar to installing a cut-out, which is another proven way to gain power over the stock exhaust.
You can gut the cat shells and re-install them, at that point they essentially become something of a 1-chamber muffler. Keep in mind that exhaust is currently flowing though those same shells anyway with the substrate in place. Having said that, you would see better gains if you installed an ORY that just eliminated the cat shells entirely. You could always just weld a piece of pipe in place of the shells to create your own ORY.
A muffler delete isn't going to hurt horsepower either. This is similar to installing a cut-out, which is another proven way to gain power over the stock exhaust.
You can gut the cat shells and re-install them, at that point they essentially become something of a 1-chamber muffler. Keep in mind that exhaust is currently flowing though those same shells anyway with the substrate in place. Having said that, you would see better gains if you installed an ORY that just eliminated the cat shells entirely. You could always just weld a piece of pipe in place of the shells to create your own ORY.
04-26-2013, 11:32 AM
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Performance is better without cats. Until 1975 nothing had cats, adding them was always a matter of emissions and had nothing to do with improving performance.
A muffler delete isn't going to hurt horsepower either. This is similar to installing a cut-out, which is another proven way to gain power over the stock exhaust.
A muffler delete isn't going to hurt horsepower either. This is similar to installing a cut-out, which is another proven way to gain power over the stock exhaust.
Be ready to think you lost power after the ORY and muffler delete. Sometimes the drastic change in how loud the car becomes confuses the mind into thinking the car is slower. When the new setup is louder under mild acceleration at 2,000rpms than the stock setup was at WOT...yeah, the brain tends to assume you're mashing the go pedal and wonders why you aren't going very fast
04-26-2013, 11:39 PM
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ok thanks for the replies. was getting p0430 which is cat efficiency below threshold so i changed the cat with a used one i got from someone and same code popped up so i figured it was by chance another bad cat so i was fed up with cats lol. didnt wanna pay 400+ for a new cali legal one so was gonna gut em and have em tuned out. turned out after i was checking over my engine i noticed that the egr gasket looked deformed. replaced the gasket and viola code is gone. go figure. i have no muffler and stock everything else and love the way it sounds now so im not gonna mess with the cats.... for now. thanks for the replies and advice.
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05-01-2013, 07:08 PM
#8
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Be ready to think you lost power after the ORY and muffler delete. Sometimes the drastic change in how loud the car becomes confuses the mind into thinking the car is slower. When the new setup is louder under mild acceleration at 2,000rpms than the stock setup was at WOT...yeah, the brain tends to assume you're mashing the go pedal and wonders why you aren't going very fast
OP I think stock exhaust LS1 w/no muffler or cats sounds like poop.
05-01-2013, 07:37 PM
#9
with the emissions in your state ,you better make sure what mufflers mite pass emissions.what will you do with the down stream O2 sensors .you need to talk to other Cali guys to see what you can get away with .
05-02-2013, 05:25 PM
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