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Discussion Starter · #1 ·
I'm getting ready to order a MK4 kit. I plan to use a Coyote Gen 3 engine since it could be made emissions-compliant with the addition of FF catalytic converter headers if I ever sell it. Since I live in Orange County, NC, emissions testing isn't required. I'm wondering if I should just go ahead and get the cat set-up even though it's not required. Would there be any disadvantages in doing this other than power loss? (I can imagine that the extra heat in the engine compartment might not be the best.)
 

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In NC it will be registered as a 65, no emissions regardless of county. Most states don’t require emissions on replicas, so it’s not going to be very helpful for resale.
Yes, cats run hot and if the tuning is off, they can get cherry red.
 

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Not sure why you think catalytic converters reduce power. Unless clogged or not properly tuned, maybe. But in general they don't. Especially for a street driven build with a Gen 3 Coyote. You'll rarely (if ever) use all the power it has anyway. Some add them because they do somewhat reduce exhaust noise. But they do generate a lot of heat and that's a potential enemy of these cars. Plus adds considerable cost. They're required by regulation in only a few instances and I doubt would be a significant factor if/when resale time comes. I've done two Coyote builds, and even without cats it's a surprisingly clean running engine. Little/no exhaust odor. Inside the exhaust tips on my Coupe with nearly 6,000 miles are still almost clean. Pretty amazing. I'd skip them.
 

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Discussion Starter · #4 ·
Not sure why you think catalytic converters reduce power. Unless clogged or not properly tuned, maybe. But in general they don't. Especially for a street driven build with a Gen 3 Coyote. You'll rarely (if ever) use all the power it has anyway. Some add them because they do somewhat reduce exhaust noise. But they do generate a lot of heat and that's a potential enemy of these cars. Plus adds considerable cost. They're required by regulation in only a few instances and I doubt would be a significant factor if/when resale time comes. I've done two Coyote builds, and even without cats it's a surprisingly clean running engine. Little/no exhaust odor. Inside the exhaust tips on my Coupe with nearly 6,000 miles are still almost clean. Pretty amazing. I'd skip them.
Thanks. That's very helpful.
 

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cats are a restriction it takes power to push it through them , i used to take the family to daytona 500 we went for 5 years leading up to the 50th, long story short wed take our suburban 95 tbi 350 2wd , wed leave michigan and drive to orlando to where my cousin lived , it took 3 tanks to get there the first year for the second year i removed the cats it took 11/2 tanks to get there my mileage jumped to near 25 mpg on the xway at 70 so if you can go with out i say go with out
 
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