Going With the Flow: An ‘Exhausting’ Look at C6 Headers
Since the early days of the automobile, people have understood that a less-restrictive exhaust system equals greater performance – and that’s why performance exhaust headers have been a staple of the aftermarket industry since the early days of dry-lakes racing.
Gone are the days of the $99 set of white-painted headers on a C2 or C3 that looked great under the hood and sounded tough; but while the Corvette itself has come a long way in performance over the years, it has relied almost exclusively on the simple, inexpensive and durable cast-iron manifolds that people have been replacing since the 1960s. (And yes, we know the C6 Z06 and ZR1 use stainless steel manifolds).
The reliance on cast-iron manifolds, even on the C6, has created a niche market in replacement headers that offer better performance than the original manifolds, but selecting them isn’t an automatic decision. Different header types, their cost and performance implications require careful consideration, so we’ve provided a quick look at everything you need to know before ordering a set of headers for your C6 – including highlighting the products of some of the industry’s most respected manufacturers.
In this article, we’ll take a look at what’s out there from American Racing Headers, Billy Boat, JBA Performance Exhaust, Kooks, LG Motorsports, and Stainless Works, as well as get some tips from the pros.
The right set of headers can complement additional engine modifications to make a world of difference for the performance of your Corvette. Choosing wisely will not only save time and money, but you’ll realize the biggest bang for your high-performance dollar.
Whether it’s a conventional exhaust manifold or a performance-oriented header, there’s more going on than simply providing an exit path for the engine’s exhaust. The length and diameter of the exhaust passages affects the velocity of the exhaust gas pulses flowing through them, creating a siphoning phenomenon called scavenging – a vacuum effect that causes the gases to flow through the exhaust tubes with greater velocity than a simple “dump” of the exhaust.
With most cast iron, production-style exhaust manifolds, there’s not too much scavenging going on, and that were headers come in. Their capability of greater scavenging through longer and typically tuned-length primary tubes creates much stronger scavenging, which helps clear more exhaust gas from the cylinder. In turn, the process enables the cylinder to ingest a larger charge of air on the next cycle. And along with more air, you add a little more fuel – badda-bing – you’ve got more horsepower.
Headers may also reduce pumping losses, making it easier for the piston to push the exhaust from the cylinder and out the pipe. Scavenging also works as the exhaust pulses move down the exhaust pipes.
The length and diameter of the header tubes can also affect the back pressure of the exhaust system, which has a significant influence on torque. There’s an entire science to determining the length and diameter of header tubes. You can assume the manufacturers we’ve highlighted later in this story have optimized their designs according to the science, but if you want to learn a little more about it, we recommend a couple of informative videos from Summit Racing Equipment on the subject.
“Shorty” vs. Long-Tube Headers
In general terms, the longer a header’s individual tubes, the more scavenging occurs at lower RPM levels, so long-tube headers have a theoretical advantage over short-tube headers – at least when it comes to horsepower. On the other end of the scale, the freer-flowing, less-restricted design advantage of long-tube headers can actually reduce torque, particularly at low engine speeds.
The desired performance balance should drive the decision on whether long-tube or “shorty” headers are the best consideration for your Corvette, but cost and installation are other important factors – especially when you consider the cost-to-benefit ratio.
Speaking again in general terms, shorty headers are typically less expensive to purchase and install, but they don’t give the maximum performance benefits of a long-tube design. And while the manufacturers of C6 headers of all sizes have gotten the fit and installation down to a science, the installation of some long-tube designs can require additional, more costly upgrades, such as new catalytic converter systems, whereas shortly headers are usually direct replacements for the stock manifolds and require no further changes.
There are also emissions considerations. Generally (but not always, so be sure to check), most shorty-style headers will be 50-state legal and/or CARB-compliant. That’s not the case with long-tube headers that require revised converter systems.
The bottom line, at least as far as we are concerned here, is that when it comes to header systems for C6 Corvettes, you’re basically looking only at long-tube headers, which aren’t legal in California.
Installing headers on the C6 is a relatively straightforward process. It’s possible to remove and set aside enough of the underhood items to facilitate a swap to shorty headers from the top of the engine compartment, but it’s ultimately easier to raise the vehicle and do the job from below. The from-the-bottom method is a must for installing long-tube headers.
In both cases, the exhaust system must be disconnected and it’s easier to simply remove it altogether. It’s also a good idea to replace at least the axle-back portion of the exhaust system with a less restrictive muffler/tailpipe setup that will help make the most of the freer-flowing headers, because there’s no use in uncorking the exhaust system at the front and keeping it bottled up at the rear.
No exotic tools or procedures are required for the header swap or exhaust upgrade, but again, having the car in the air makes all the difference in the ease and speed at which the project can be completed.
It can cost several hundred dollars to have headers installed professionally, with long-tubes logically costing more to install than shorty headers. Long-tube installation may also require tuning that will add to the cost.
With new headers installed on an otherwise stock engine, you can expect anywhere from 10 to 45 more horsepower at the rear wheels with the range of long-tubes currently on the market for C6. That’s a general rule of thumb, but the payoff is even larger if you have or are planning more extensive engine modifications – especially a head-and-cam package or supercharger.
Keep that in mind as you plan performance mods to your C6. Headers are a great complement to more serious performance modifications, but given their cost to purchase and install, they’re not necessarily the best bet for a simple bolt-on upgrade. If you want a throatier sound and a few more rear-wheel horses, start with an axle-back-type exhaust system. Make the investment in headers when you’re stepping up engine performance with serious mods.
The final thing to keep in mind about headers is, for the most part, they’re loud – at least, relatively speaking. There’s a reason the OEMs continue to use thick cast iron manifolds, besides their inexpensiveness: They’re quiet.
We’re guessing that if you’re reading this to help determine which headers you want for your C6, the exhaust engine noise isn’t something you’re worried about. Heck, you’ll probably enjoy the additional rumble – especially if it’s mixed with a lumpier camshaft profile – but we felt it was important to bring up. Consider yourself duly apprised.
Our advice is to invest in headers when you plan to go deeper into the engine with camshaft or more. You’ll get the best bang out of your buck. And when you’re ready to make the plunge, here’s a representative cross section of what’s available on the market.
American Racing Headers
American Racing Headers manufactures only long-tube header systems for the C6 Corvette, but offers them for the LS2/LS3 models, the Z06 and ZR1 – all including necessary after-header crossover tubing to replace the original exhaust tubing. The headers and crossover pipes are made of 304 stainless steel.
“All our systems come standard with merge collectors with scavenger spikes,” says American Racing Headers’ co-founder Nick Filippides. “We also use the highest quality and best-flowing metallic-substrate catalytic converters available.”
The headers for LS2 and LS3 models are offered with 1-3/4-inch or 1-7/8-inch primary exhaust tubes and 3-inch merge collectors. The Z06 and ZR1 headers are offered in the larger-diameter 1-7/8-inch-primary size. The LS2/LS3 1-3/4-inch headers are offered with a 3 x 2-1/3-inch after-header crossover pipe (with or without catalytic converters), while all of the 1-7/8-inch headers include a 3 x 3-inch crossover pipe.
Importantly, the long-tube design and replacement converter system makes American Racing Headers not legal for street cars in California. You’re good to go if it’s strictly a race car, but there’s no CARB approval for running them on the street.
JBA Performance Exhaust
JBA Performance Exhaust offers three different header designs for C6 Corvettes, including the Z06, all made from 400-series series stainless steel, which is some pretty durable stuff. Additional features shared among all the headers are 3/8-inch-thick flanges, JBA’s patented Firecone Collector merge – which features a cone-shaped separator at the base of merge to enhance flow – provisions for oxygen sensors and mandrel-bent tubes for optimal flow.
Per JBA’s Don Lindfors, “As with all JBA headers, they’re available in a variety of coatings, including raw stainless, Bright Silver Metallic ceramic-coated and Titanium ceramic-coated.”
Also, all three of JBA’s C6 headers use a leak-proof stainless steel V-band collector clamp arrangement and the company also offers the requisite mid-pipes to install behind the long-tube headers – and like the headers, they have the necessary oxygen-sensor bungs and, where necessary, the kits include sensor extension harnesses.
Kooks Headers and Exhaust
Kooks quickly established themselves as one of the premier manufacturers of C5 and C6 Corvette header systems (as a matter of fact, our own Project Y2k wears a set of them) and their range of 49-state-legal 1-7/8-inch-diameter long-tube headers covers all iterations of the C6 to roll out of Bowling Green. Like other manufacturers, their lineup includes the mid-tubes, and they even offer systems with high-flow converters.
“Everything is made at our facility in North Carolina and we do all the R and D here,” said Kook’s Chris Clark. “You can typically install a complete system in about two or two-and-a-half hours. No cutting, no welding – you just bolt it right in and go.”
Billy Boat Performance Exhaust
Since 1990, B&B has been producing exhausts for numerous Porsches and BMWs, but in the mid ’90′s, the brand expanded to producing exhausts for Corvettes and other domestic vehicles as well as European and Asian vehicles. The header systems that Billy Boat offers for the C6 range from 1-3/4″ primary tubes to 1-7/8″ stepped to 2-inch primary tubes that lead to a 4-into-1, 3-inch collector and are available for all engines offered in the C6 generation. “You go to a long tube header to help the engine scavenge and help it operate more efficiently. We try to get our tubes as equal length as possible and then also look to get a balance between tube size and performance,” explained B&B’s Billy Boat.
For incredibly efficient exhaust scavenging, their header design implements correct firing order which, in turn, pairs exhaust ports together. Typical power increases that B&B usually sees is around 45 horsepower and 40 pound-feet, and the header systems can also be paired with one of their 2 1/2-inch or 3-inch x-pipes for even exhaust pulses, and ultimately, a smoother tone. Their x-pipes are available with or without catalytic converters for states that strictly enforces emissions laws. Prices for B&B’s header systems start at $1,325.00, which is a great price for those looking to spiff up the performance of their Corvette.
If you’re looking for a complete exhaust for your C6, B&B has you covered – they offer an exhaust for any sound level the owner wishes their ‘Vette to have. The Bullet exhaust system, the PRT exhaust system, which utilizes their new Purge Resonance Technology that negates the annoying drone of a loud exhaust, the Route 66 system, and the C6 Fusion exhaust with controllable valves can be used with the various header and x-pipe options to obtain the great sound that the customer is looking for.
Texas-based LG Motorsports is rooted in racing, and their range of long-tube headers for C6 Corvettes reflects that with their track-oriented Super Pro Long Tube headers in 1-3/4-inch and 1-7/8-inch sizes for LS2, LS3 and LS7 engines – with the 1-7/8-inch headers designed for all-out, uncompromising performance.
The key to the headers’ performance, according to LG, is a unique, “true competition” merge collector with a fire-cone design that helps maintain greater torque and horsepower at the upper RPM range. The company also offers a less-expensive Street Series long-tube header system that will save a few hundred bucks for those looking for a good balance of performance and sound on cars not intended to spend all their time on the racetrack.
“We pride ourselves in making the most power under the curve than any other manufacturer,” says LG Motorsports’ Anthony Forney. “And we were the first to design, market and build a true bolt-on header kit, from front to back, with no modifications needed to your Corvette.”
LG Motorsports tells us typical gains on with Street Series-equipped system and a tune can see 25-30 additional horsepower and 30-40 pound-feet of torque. Pro Series systems can see upwards of 28-36 HP and 35-50 pound-feet of torque or more, depended on the application and other upgrades.
Offering the only 2-inch-diameter primary tubing on the long-tube headers in our guide, Stainless Works also produces traditional 1-7/8-inch headers, all for 2099-and-later C6s – sorry LS2 owners. And like some other kits, they’re available with or without high-flow cats and the kits include a 3-inch X-style mid-pipe.
We like that Stainless Works also offers their own axle-back muffler system to complement the headers. All in, you’re looking at about $2,500 for the two systems, which would give you a full exhaust system, from the header flanges bolted to the engine to the exhaust tips peeking out beneath the rear fascia. The components are all made of 304 stainless steel, too.