We only halfway realized what we were getting ourselves into when we got our '66 Mustang project car. Having more experience with the '68 Camaro, I didn't know much about the differences between early Mustangs, and just got what looked like a good solid car to start from. Over the months, we've come to realize that the '66-and-older Mustangs are one of the most difficult to work with. They have a narrower engine bay and transmission tunnel, making engine fitment a challenge. Like most high-horsepower engines we build, we wanted to get a set of long-tube headers to allow it to breathe. The clearance between the Windsor's heads and the inner fenders posed a problem. Also, the AFR heads used by Smeding have a raised port of almost a half inch. This combination of problems meant selecting a header would be difficult. With much research, the closest set of headers to what we needed were Pro Comps by Hooker. They were a long-tube style for a Windsor motor in a '66 Mustang, but in the description Hooker notes that there could be floor clearance problems with raised-port heads. Looking for affordable out-of-the-box headers, we thought we'd give it a try. They were right; the raised ports were just high enough to lose all our floorboard clearance. Wanting to keep the price reasonable, we started looking into mid-length headers that would keep that problem at bay. Our search ended at Doug's Headers.
Doug's Headers started out as a small shop in East Los Angeles in 1958, and has grown into an extremely reputable header and exhaust component manufacturer. In 2000, the company was bought by Pertronix Performance Products, which gave Doug's Headers more resources than ever. Lucky for us, they had something for the Street Fighter Mustang. We really liked the look of the Doug's stainless steel set, so that's what we got. They said the 409 stainless would discolor over time to a black and gold tone, which actually sounded kind of cool. This set is part number 1653S from their catalog, and can be purchased through Summit Racing for $589.95.
We weren't planning on getting these headers coated, but if we were, we'd want to test-fit them first since our first set didn't fit. The engine bay, if you haven't seen firsthand, is impossibly small. It took lifting the car to the maximum height allowed by jackstands, along with the engine lifted until the bellhousing barely touched the transmission tunnel. The good news is that the engine doesn't have to come out to get these headers in, and they are made to work with or without raised-port heads. They use a two-bolt ball-and-socket flange that seals great without gaskets-a big plus in a tight engine bay. The primary tubes are 1 5/8-inch, which just squeezes by the inner sheetmetal, then collects at a 2.5-inch tube before the flange. One of the most important things about headers, besides the fitment and tube dimensions, is the flange thickness. There are few things more annoying than an exhaust leak at the head-side flange, so Doug's equipped these headers with beefy 3/8-inch flanges and special gaskets. This Mustang will be started for the first time in the car with open headers, but a full exhaust system is on the way.