Will headers or cats be louder with NPP wide open in track mode? I want loud but with performance and that’s the reason I haven’t included a cat back.

 

Bill,

You will see see an increase in sound with our headers, not to mention significant performance gains. The majority of the sound increase will be with the valves open for sure. Our in-house testing didn’t show any appreciable gains in power with performance cats, and thus our focus on sound wasn’t deterred. Allowing the engine to breathe through a quality set of headers will have an increase in sound as a byproduct. There’s no getting around that.

Nick

 

Yea I know that’s why I want your headers but someone on the FB page said he heard 0 gain in sound when he installed your headers and that worried me so that’s why I put in this question for other members feedback.

I really like the npp because if I get pulled over I can switch it over and make it quite or when I leave in the early am.

also waiting for you to release HTC version or help you test fit.

 

HJS large German Cats from FabSpeed are great mod adding in a much deeper growl to the NPP exhaust without going to completely Wild and keeping the NPP exhaust.

With the HJS Cats add in 6.5HP/6.5TQ rear wheel and deduct 9lbs. Also like the heat insulated military grade heat blankets providing better heat protection than the GM OEM cats.

Also does not void your warranty or throw any codes.

Here is a comparison sound clip with the NPP and High Flow HJS Cats:


Also a FabSpeed clip on the large HF HJS Cats:

https://www.youtube.com/watch?v=JD0Y...ature=youtu.be

 

Yea 6hp is 6 hp but like i said the most with sound for the $ those are $3k ... nothing will guarantee it wont affect the warranty and completely illegal in the good old state of CA.... that gas smell really gives it away to law enforcement. That being said if its the best for sound and HP i will go with it

Also love how the video in the revs and the driving in front of the shop they dont get on it as hard when its stock but they get on it real hard with the cats

 

Bill,

We've had two C8's here with just our headers installed. There most definitely is an increase in sound but the majority of that increase is with the valves open. Closed and at idle the difference is minimal.

Nick

 

So you also tested cats out.... if you have heard whats your opinion in sound high flow cats and NPP open or headers and NPP open which is louder?

 

Definitely will hear a bigger increase in sound with high flow cats over headers. Fabspeed and Soul use the same HJS 200-cell cats, so they should sound about the same (and cost is nearly identical). Kooks uses a 400-cell cat in their ultra green cats, I would expect it to be a little quieter than the other two, but also possibly slightly better for emissions. The real question is it worth the cost. An X-pipe with high flow cats for my Mustang cost me around $600. This $2k-$3k stuff seems excessive to me.

 

Our Sport Cats don't have the raw fuel smell you're referencing. Despite the improved flow, the Euro 6 grade HJS Catalyst cores do a phenomenal job of cleaning up the exhaust. No Check Engine Light Guarantee. No tune required. The car will pass OBDII testing, as well as an exhaust probe sniffer test. You are correct that we do NOT carry CARB approval and we do not have an EO number for them - so they would fail a visual inspection only. California is our largest market in the US - and I doubt very much all those cars revert back to stock every time they have to pass emissions, so I'm not sure how those individuals navigate those waters.

Since our Sport Cats flow 85% - 90% of cat bypass, you get sound very close to a cat bypass option.

Our Valvetronic exhaust might be worth a look as well - as I believe it's still the only aftermarket performance exhaust currently available with valves. It's certainly louder than the NPP but still retains the Quiet/Loud functionality of a valved system. The valve operation of our Valvetronic seamlessly mirrors the OEM opening and closing parameters directed by the different driving modes. A bit more expensive than the Sport Cats, but my understanding is California has gotten much more relaxed on emissions testing regarding cat-back exhausts, and CHP has relaxed on noise levels as well. So this option might have fewer objections and obstacles than the cats.

Black Friday / Cyber Monday pricing is in play.

 

Really no smell because i have heard a few complain and even 1 person switch back to stock because of the smell.
All they do now is a visual and checking #'s on the cat and OBD... i have an 06 charger camed headers and cut out suitcase intake and tuned and passed the OBD and was passing the visual but he knew something was up and was looking hard to find it but never saw the headers as my cat was stock and I just cut the suitcase out so I passed. I mean if i fail the visual in 6 years i will switch it out.

 

You are seeking 2 different things. If you want loud, a high flow cat is prob the way to go. If you want performance then the headers are the easy choice.

Noise only=cats
20-30hp bump=AR headers

 

I was waiting for you to chime in. Yes I get it loud is cats and power is headers. But i am looking for the best balance. Chevy Dude did a db test with his cats and NPP and it was like 10dbs louder. If say the headers are say 7+ dbs louder its a no brainer headers. But if say headers was only 1-3 dbs louder then its a tougher decision.

I do like your set up and your gains. I know where you got the TB did you just clean up and polish your intake manifold yourself? I forget what else do you have done?

 

I know their was definitely an audible difference with the headers over the stock manifolds but I don't have a decibel meter to help you out with that.

Appreciate the kind words, I thought the IM was pretty good from the factory and just needed a seam cleanup but after I put a micrometer on the head runner and the IM their was a 3-4mm difference, so I got to grinding !! It's not a port match, but for me it will do.

 

Is there a Black Friday Code to enter for Fabspeed?

 

Negative - the discount structure will automatically apply when the sale officially launches Friday 11/20.

We can draft detailed Quotes manually in the meantime to apply the discount prior to launch. Feel free to hit me at joe.torchiana@fabspeed.com to take advantage of that opportunity.

Since our products are handcrafted per order, that will allow you to get ahead of the log jam of the procrastinators who wait until Black Friday and Cyber Monday itself. We typically get a week's worth of orders on each of those days - so lead times will likely get a bit longer.

 

This is the second thread I've heard 20-30hp from headers and I'm not so sure.

This was ARH's baseline:


Call it 447hp and 412tq (or 439hp and 405tq with WCF weather correction factor).

Then in this R&D video for three variations of the header - 1 3/4", 1 7/8", and 2.0":


If you look closely, the baseline in this video is still listed as 439hp (not sure if that's WCF or not). But look at the torque, it's only listed as 393ft lbs - 12 ft lbs lower than the WCF baseline of 405tq in the previous video. So the claim of 17hp makes sense, 439 --> 456 but I question the 33ft lbs of torque due to the varied baselines and where those 12 extra foot pounds went.

Nick references no appreciable gains from cats, but he mentions they used 300 cell cats - which wouldn't flow as well as 200 cell. He makes a point to reference the physical dimension of the factory cat with a 6" face, but does not mention the physical dimensions of the aftermarket high flow cat that was used. So with all these variables in play, there are a lot of questions about the final results and the numbers.

 

For what its worth.....
Im not sure what kind of business you run but its really starting look bad that you are always talking bad about your competition. As a very successful sales professional that is the # 1 thing NOT to do. What's even worse is its not even the same product.

Ill probably get in trouble for saying this since your a supporting vendor but whatever

 

Our business has been focused in high performance platforms for over 25 years. We are excited to be a part of the C8 community - our first dive into the Corvette. To be clear, we have no issue or bad blood with ARH whatsoever - they've been in the game a long time, and have a great reputation in the domestic scene. I have personally supported and sold the ARH brand in a previous position with one of the largest wholesale distributors on the planet, Turn14 Distribution. So there is really no beef or axe to grind.

Fabspeed is totally objective in this case - we don't manufacture headers for the C8 and we don't plan to do so. We don't have any affiliation with any header manufacturer (other than the headers we produce ourselves for other platforms).

Forums can be an incredibly valuable source of information. They can also be a source of misinformation. As a passionate enthusiast myself, I crave clear and accurate information - in this example, various data points don't seem to align.

When a claim is made that a part can produce upwards of 30hp (ARH did not make this claim by the way - a private user did), and all evidence from the manufacturer shows the documented figure is closer to half that (17whp) I think it is absolutely valid and fair to note that inconsistency - no matter the manufacturer or part - for the benefit of maintaining accurate information within the community. There was no name-calling or finger-pointing, merely an encouragement to analyze and re-evaluate the information provided by the manufacturer. When I took a look at that information provided by the manufacturer myself, I noted additional inconsistency in the figures themselves in the two videos.

If we're not all enthusiasts seeking accurate information about the cars we drive, why are we on here? If false inaccurate information is taken as gospel, and then regurgitated later, you can imagine the implications. It's whisper down the lane with a keyboard.

Personally, I would love to see the results of ARH paired with our Sport Cats - which are 200 cell and have a cross section of 5.62". I'm sure the pairing will happen eventually - and will make good power. A lot of dyno testing out there seems to indicate that there is a symbiotic relationship with headers and high flow cats used together - with greater total gains than the sum of gains of each individual part.

No need to be bashful. You won't get in trouble. We appreciate your candor, and feedback - even if it's not complimentary. Open dialog is another fundamental purpose of this forum.

 

All our test results were weather corrected. And yes, I did mention that the cats were 300 cell and were dimensionally smaller. 4" OD to be exact, which as we all know is the industry standard on practically all aftermarket header systems. I clearly mentioned that our testing showed no appreciable gains with the cats we tested as we felt the OD of the factory cats easily offset the higher flow of the smaller diameter aftermarket cats. It's possible that what you're offering is better as they are larger dimensionally and have a reduced cell count. Our results with our header system was rock solid and backed up immediately after delivery by Snowblind 2.0 on an independent dyno. He baselined his car prior to dropping if off. There is absolutely no disinformation in anything we posted.

Nick

 

Got it and thanks for the clarification Nick! The 12ft lb difference in the baselines had me confused. If the 412tq (405tq WCF) figure from the first video and the 393tq of the second video were on different dynos, that absolutely makes sense.