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oldman · 10-26-2016, 08:22 AM

modern cats are worth say -5 HP.

Not -20. Nothing wrong with the cats (IMO), many high flow cat systems over the last 20 years send a check engine light, some every once in a while, some frequently. The cat / exhaust just flows too much to pass factory check engine light parameters. For the most part the light does not affect performance.

Here sock: 410 HP, headers and cats: 430, headers, cats and full exhaust 438 HP. About 20 HP for full length headers and high flow cats. Ya thinking how much more with off road pipes? I say 5.

Catted system that just wont last? what do you mean? The cat did not fall out of the car. High flow systems generate check engine lights. I don't own a 5th gen, so maybe not much of a problem on that one model. It is a problem on all cars that I know and mod. The header cat systems are working but not working within the parameters of the OEM check engine light. I for one knew that going in. Even a CAI CAI, MSD intake manifold, and missing front cats (turned off via HP tunner) will throw lean codes every once in a while.

You find me ONE just ONE vendor that says you won't get a check engine light for something like cat inefficiency on a cold day. The green cat system will pass smog in 49 states, it is no fail safe against a check engine light. I've modded late model Challengers, Volvo, Honda, Acura, VW and a few trucks. Let me think hmmm... yep every one would throw a check engine light every once in a while. IMO if you can't handle that keep it stock.

Here is an actual quote from a shop that has done a Kook's header cat on a 6th gen:"“These catalytic converters have an EPA certification and a proven track record, with a 90 percent success rate of keeping the check engine light off,”
Alvarez said"

I'll convert that to plain English as 100% chance that you get a check engine light every once in a while, that won't hurt noting.
http://www.chevyhardcore.com/tech-st...-tube-headers/
Or you can whistle in the dark and think modding your ride with no ability or want to tune is not going to throw any code ever... more power to you, just does not happen in my reality.

10-26-2016, 08:22 AM	#34
oldman Drives: SS 6 speed of course Join Date: Jan 2016 Location: Hilo, HI Posts: 4,346	modern cats are worth say -5 HP. Not -20. Nothing wrong with the cats (IMO), many high flow cat systems over the last 20 years send a check engine light, some every once in a while, some frequently. The cat / exhaust just flows too much to pass factory check engine light parameters. For the most part the light does not affect performance. Here sock: 410 HP, headers and cats: 430, headers, cats and full exhaust 438 HP. About 20 HP for full length headers and high flow cats. Ya thinking how much more with off road pipes? I say 5. Catted system that just wont last? what do you mean? The cat did not fall out of the car. High flow systems generate check engine lights. I don't own a 5th gen, so maybe not much of a problem on that one model. It is a problem on all cars that I know and mod. The header cat systems are working but not working within the parameters of the OEM check engine light. I for one knew that going in. Even a CAI CAI, MSD intake manifold, and missing front cats (turned off via HP tunner) will throw lean codes every once in a while. You find me ONE just ONE vendor that says you won't get a check engine light for something like cat inefficiency on a cold day. The green cat system will pass smog in 49 states, it is no fail safe against a check engine light. I've modded late model Challengers, Volvo, Honda, Acura, VW and a few trucks. Let me think hmmm... yep every one would throw a check engine light every once in a while. IMO if you can't handle that keep it stock. Here is an actual quote from a shop that has done a Kook's header cat on a 6th gen:"“These catalytic converters have an EPA certification and a proven track record, with a 90 percent success rate of keeping the check engine light off,” Alvarez said" I'll convert that to plain English as 100% chance that you get a check engine light every once in a while, that won't hurt noting. http://www.chevyhardcore.com/tech-st...-tube-headers/ Or you can whistle in the dark and think modding your ride with no ability or want to tune is not going to throw any code ever... more power to you, just does not happen in my reality. __________________ Forged short block, large duration sub .600 lift Cam Motion cam, 7200 RPM fuel cut, Pray Ported Heads, 3.85 pulley D1X, stage II intercooler, DSX secondary low side, DSX E85 sensor, Lingenfelter big bore 2.0 pump, ported front cats, 60608 Borla, LT4 injectors, ZL1 1LE driveshaft and Katech ported TB, ported MSD intake, BTR valvetrain, ARP studs, ProFlow valves, PS4 tires. Last edited by oldman; 10-28-2016 at 08:13 AM.