Header Performance Guide For Mustangs
Choosing The Right Headers For Your Mustang Requires An Understanding Of What Header Design Does For Performance
Headers and exhaust systems have become something of a cliché because everyone talks about them, yet not enough of us know how to choose them. We select headers for all kinds of reasons, many of them having nothing to do with performance. These days, it's more about how they look against a cylinder head and valve cover versus how they perform.
And contrary to what you might believe, headers don't always improve performance. Sometimes, they hinder depending on design. If you're running the same headers on your 427W stroker that you had on the 351W it replaced, you don't have enough header. You need larger header tubes and collectors to handle the increased exhaust gas volume. By the same token, header tubes that are too large will rob you of torque because there needs to be back pressure to make torque depending on valve overlap.
Another important element to header design, aside from performance and good looks, is how they fit. You want an exhaust header that cannot be seen hanging below the car when you look at a side profile of your Mustang. Headers that scrape speed bumps are a bad idea. If you're building a weekend racer, low hanging collectors aren't as critical. For street use, it becomes annoying every time you broach a parking lot.
When you think of PerTronix, you think of innovative ignition systems and ignition retrofits for classic Mustangs. However, PerTronix also has its own header brand, Patriot Headers, and they have acquired a couple of reputable exhaust manufacturers in recent years-JBA Headers and Doug's Headers, which has been around since 1958 and trusted by untold thousands of enthusiasts, including Shelby American in the 1960s.
We spoke with Don Lindfors at PerTronix Performance Products Exhaust Group about choosing headers for Mustangs.
MM: What kind of header do you recommend for classic Mustangs?
DL: The first question you need to ask is why you want headers in the first place. Are you looking to improve mileage or increase power? Do you have a high-performance engine that needs increased exhaust flow, a different sound, etc.? The next thing is the intended use of the car. Is it a daily-driver, a full-blown racer, a street/strip car, or a lowered Pro Touring-type car. With these questions answered, you can make an educated decision as to what best fits your needs. We look at classic Mustangs separately from late-model Mustangs because there are some very important differences, including the fact that in most states classic Mustangs are exempt from emission laws so you don't have to be concerned with that.
The PerTronix Exhaust Group offers several different types of headers for classic Mustangs. Shorty headers improve performance with excellent ground clearance and are a great way to go for lowered cars and stock or mild engines. Long-tube Tri-Y headers were pretty much invented for Mustangs, and Doug's Headers was one of the first in this segment. Tri-Ys offer big boosts in power across the RPM range and slightly better ground clearance than a traditional four-tube header, plus Carroll Shelby used Tri-Ys on his legendary GT350s. Four-tube, full-length headers are the most common type of header. They make big horsepower gains including at high RPM, but they usually sacrifice ground clearance. There are also specialty headers for engine swaps in classic Mustangs.