About to order HKS header & front pipe. To go cat or no cat?

[trd_kid]

I have a stock header with an HKS resonated front pipe, and tomei 60s on stock tune. With this setup I do get soot buildup on the exhaust but it's not bad where I have soot on the rear bumper. I know it's not the exact setup you want , but hopefully it will help you make your decision.

[ramiram1984]

I had CEL on my catless hks header, even after a tune...

[cdrazic93]

Cat vs no cat. Fluffy vs no fluffy.

Catalytic converters offer resistance to air flow. These are most prevalent in stock cats.

Now, high flow cats are literally at the minimal limits for catalytic converters. In a regular stock cat comparison, you can shine a flashlight through the stock cat and not see anything on the other side, you'll blind yourself if you try that with a high flow cat. Remember this is all about restriction of the air flow, so unless you're pushing about double the hp, you will not see any difference in whp relating to cat vs no cat. I see no benefit of having 2 either, get a catted header and catless front pipe, or vice Versa.

[jng]

Thanks all. The only reason I am considering a catless front pipe (vs. a catted one) is that I can get a very good deal on the catless one. Will give it a go and see if the soot build up becomes too excessive.

[AVodka14]

The only cat I ran on my old tC was in the header (factory manifold/primary cat) and that made a big difference in sound compared the aftermarket header without a cat. Without the cat in the header. The car sounded horrid. I will run as many cats in my exhaust if I plan going full as possible. Sound over slight HP gains. I don't care because I am going turbo. Let us know how you like it. Cheers!

[Deep Six]

Originally Posted by jng

Does anyone have the HKS EL header + resonated front pipe combo (both un-catted) installed? Does the lack of cat for both cause black soot build up at the bumper / exhaust tips for NA car running without a tune?

Any comparative thoughts on the HKS resonated front pipe (catless) vs. stock front pipe?

Thanks.

I have both of them paired with a 3" exhaust. The tips get some soot build up that cleans easily with metal polish but because they extend just past the diffuser, the bumper stays clean. I will tell you it's loud enough to drown out any cabin conversation so keep that in mind when selecting a cat back to go with a cat less setup.

[jng]

Am already running Greddy Trust CS GTS v. 2 catback, which is relatively quiet. Is the increased loudness mainly from the header or front pipe?

[jng]

Freshly installed HKS EL header + front pipe (both un-catted), with stock overpipe and Greddy/Trust CS GTS v2 catback. No CEL, as I understand is typically the case with HKS exhaust parts on the Middle East / Asian spec models.

Revving, especially in the lower gears, is noticeably significantly louder in the inside of the car. I can really smell the fumes as well, which tend to seep in especially when I am stationary at the lights. Will give it a few weeks before I decide whether to revert to the stock front pipe...

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