Exhaust Systems
Like mufflers, Holley offers multiple exhaust systems for a variety of applications, each with different tones and sound levels. When choosing an exhaust system, keep in mind not only the external sound level but the sound level inside the vehicle as well. You should also note the material that is used in the system’s construction. Aluminized steel is less expensive and a good option for applications that do not see regular use in harsh weather conditions. 409 Stainless Steel offers a more durable solution and has more corrosion resistance. 304 Stainless Steel offers even more corrosion resistance and can be polished out for a car-show-like appearance.
H-Pipe VS. X-Pipe
Flowmaster strongly recommends using a crossover pipe in all 'true' dual exhaust systems. The crossover system equalizes the exhaust pressure exiting each bank of the engine, allowing the engine to run more smoothly. The crossover generally increases low-end and mid-range torque and delivers a smoother overall tone to the exhaust.
Crossovers are commonly known as H or X-pipes. These two types perform the same function in somewhat different ways. While H-pipes provide a simple pressure equalization avenue, X-pipes tend to trade some exhaust flow from side to side. In both dynamometer and real-world on-vehicle testing, it has been shown that the two designs generally provide almost identical performance benefits in many different applications. Common exceptions are engines operated at sustained high RPM (8000+), where X-pipes show a small edge over H-pipes.
In some instances however, it has been shown that X-pipes, especially when combined with Flowmaster mufflers, can 'over scavenge' an engine, causing performance (horsepower) losses. A very important point to remember is that every engine and vehicle combination is different, and what works well on one vehicle might be completely wrong for the next.
Tailpipe Length
Flowmaster highly recommends running a minimum of twelve inches of tailpipe after the muffler(s) on street-driven vehicles. This not only provides better sound control but also delivers an increase in usable performance. Exiting exhaust out from under the vehicle also reduces interior sound levels. Race vehicles, due to different performance requirements, can use shorter tailpipes or turndowns for space/weight considerations.
Catalytic Converters
Flowmaster’s Catalytic Converters are designed to fit and function on a large variety of vehicles, and all our new Direct-Fit Federal Catalytic Converters are designed to meet or exceed both OE and USEPA standards. Only the highest quality materials are used to manufacture these converters. Stainless steel outer shell and heat shield construction provide long-term durability, while OEM-grade substrates carry the noble metals and meet or exceed all OEM and 49 State USEPA emissions standards. Our converters have been engineered specifically for maximum efficiency and effectiveness to avoid the ‘MIL’ (check engine light) trouble code issues common to low-quality converter use. Our California catalytic convertors meet OEM and CARB emission specifications and are covered by our 5 year/50k mile warranty for exterior casings and 50k mile warranty on interior components ensuring you meet California emissions standards, or we'll replace it for free.
When a converter replacement is required, installation of universal models should be accomplished by a qualified technician familiar with fabrication, welding, and basic emissions requirements.
