Hey guys, I'm using rb header, he's dragger mufflers, and high flow cats. I'm doing true duels to keep the car quieter wile having a low restriction exhaust. My question is should I place the cats close to the header or closer to the mufflers?

 

Spell check always gets me. I'm using hks dragger mufflers.

 

Why are you planning to install the cats in the system? There's not much room between where the header comes down and connects with the presilencer and I would be hesitant to make changes to the header for power reasons. Are you required to run cats for emissions?

 

they NEED to be under the stock heat shield, they get hot enough to melt things, like the carpet

 

And don't they need to be hot to work good and that's why car manufacturers put them close to the engine, because they need to be?

 

I'm not using a presilencer. I'm only using rb long header, 2 hks mufflers, and 2 open pipes connecting them. I want to instal cats for noise levels and for local inspection requirments. With how open the exhaust will be, I'm curious how close to the header they should be. I don't want to burn or plug them up. Im hoping someone on here has some experience to save me some time. But if I don't get any useful info then I'll just mock the system, measure temps, and mount them as far back as possible within a proper heat range.

 

Jesus Christ.

You already have the useful information. It really doesn't matter how "open" it'll be. It's the best location for safety and use.

Good luck fitting them.

 

they need to be under the stock heat shield. i built a car where the cat was like 1/2" behind the heat shield, and it smoked the carpet.

b the cat starts working at about 450c, and starts melting at 650c, so if you put an EGT in the cat inlet, that gives you your guidelines. you will end up with a tune that most people would consider odd, but if you want the cats to live you need to give them what they want.

having two cats should have enough flow that they won't offer a restriction, so you should be pretty happy there

 

Or you can do what the stage rally guys do and use the cat as the exhaust tip. It won't do much back there but it also won't melt down, probably, if you use a nice steel-substrate unit. As a bonus, following traffic gets to see the glowing-orange brick.

They have also come down a LOT in price! A good motorsports cat used to be in the $1000 range. Now they're down in the $150ish range give or take.