A true dual exhaust was the hot ticket until enthusiasts started adding H-pipes to change the sound and performance of traditional two-pipe systems. Unfortunately, turbulence in the merge area led tuners questioning how they could eliminate firing order pressure differences between the right and left banks of the exhaust manifolds, and free up more horsepower. The eventual answer to the question was the X-pipe exhaust equalizer system. The X-junction smoothly blends exhaust pulses from the left and right side engine banks to produce a smooth exhaust note, and increase volumetric efficiency of the entire system, resulting in increased power. Dyno testing of Hedman's system for a 1985 Mustang GT, by a leading Mustang publication, demonstrated an increase of 35.3 Horses and 28.5ft lbs. over the stock, baseline dyno pulls. While the benefits of an X-pipe system are evident after a single test drive or dyno pull, and universal fit X-pipe models may be plentiful and flexible in design, they are not the easiest systems to install. Hedman Hedders helps out Mustang owners, however, with its selection of direct fit, X-Treme X-Pipe Exhaust Equalizer Systems for 1986 to 2007 Ford Mustang V8s. Hedman's 2-1/2 inch, mandrel-bent X-pipe systems easily bolt up to the factory headers and muffler/tailpipe section using factory style flanges. And, even though all X-pipe systems, including those with catalytic converters, are legal for off-road or competition use only, Hedman still installs oxygen sensor bungs in the thick 16-guage aluminized steel systems to keep the engine management system happy. Made in the U.S.A. at their Southern California facility, Hedman’s X-Treme Exhaust Equalizer Systems are available for 1986 to 1993 (Part #18814) and 1994-1995 (Part # 18115) 5.0L Mustangs with factory headers and exhaust system. Owners of 1996-1997 (Part # 18816) and 1998-2004 (Part# 18817) Mustangs with 16-valve 4.6L engines can also enjoy Hedman's direct-fit, easy to-install X-pipe systems. A system is available for 2005-2007 (Part# 18860) 4.6L 3V pony cars, however this system has been designed for use with Hedman's long tube headers only. All models are engineered to work on both manual and automatic transmission Mustangs.