| Kit No. | Specifics |
| 17273 | 2 ½" with Series 40 Delta Flow Mufflers and polished stainless tailpipe tips. |
| 17334 | 2 ¼" with Series 50 Delta Flow Mufflers and polished stainless tailpipe tips. |
| 17281 | 2 ½" with Super 44 Mufflers with polished stainless tailpipe tips designed for the GT valance. |
| 17282 | 2 ½" with Super 44 Mufflers with turndowns for non-GT valance. |
Delta Flow
How do you improve on a winner? Flowmaster calls it Delta Flow. Born from the Delta Force racing muffler, the new street muffler offers exciting technology that provides superior scavenging over conventional mufflers. Delta Flow technology uses additional deflectors to provide a cleaner, faster scavenging path for hot exhaust gases to virtually eliminate turbulence. Here are the benefits of Flowmaster's new Delta Flow muffler.
Resonant tuning chamber captures and cancels specific sound frequencies, which reduces resonance inside the cabin.
Power chamber creates a negative pressure (suction) that helps scavenge exhaust gases. This means more power, better low-end torque, and to some degree improved fuel economy. It also reduces exhaust system heat.
Low pressure balance chamber blocks power-robbing atmospheric pressure from adversely affecting exhaust system function.
Delta Flow Technology provides advanced noise cancellation by separating and recombining exhaust pulses at precise phase shift. In other words, quieter operation.
H-Pipe Or X-Style Crossover?
Why should you tie both sides of a dual exhaust system via a crossover pipe? Aside from how it affects sound, it is also important for performance. The crossover balances cylinder bank exhaust pulses on V-6 and V-8 engines. When you separate cylinder banks, you get a popgun sound from dual exhausts. Mixing it up allows the banks to complement one another. It also improves scavenging.
Boyd Butler of Pro Motorsports Engineering pioneered the X-style crossover-a crisscross pipe design that smoothes exhaust flow across cylinder banks. Without question, and consistently proven in stock car racing, it frees up horsepower and torque. The X-style crossover does its best work at high rpm.
Should you install an X crossover on your Mustang? If you're going racing or you like the bizarre, buzzy sound and high rpm of an X, then yes. If you're going cruising or building a show car, it's your option. The X-style crossover does improve performance, so you can expect some improvement in power.
 If you're adding dual exhausts...  If you're adding dual exhausts to a Mustang that didn't come from the factory with duals, don't just drill holes in the floorpan and hang mufflers using sheetmetal screws. Use the factory hangers and stud plates, which are worth the investment. We used not only the stud plates provided by Virginia Classic Mustang, but also the electrical junction box side plates made of heavy gauge galvanized steel. Visit any home improvement store and ask for heavy gauge galvanized steel and make reinforcement plates for your floorpan, which ensures solid exhaust system hanger security. |  Tailpipe positioning is tricky...  Tailpipe positioning is tricky because it mandates proper muffler positioning. If mufflers are too high or too low, you will never get the correct tailpipe angle. That's why fitment must include H-pipe, exhaust pipes, mufflers, and tailpipe before permanently anchoring anything. Ascertain proper clearance and position before welding. |  These are 23-inch Flowmaster...  These are 23-inch Flowmaster Series 50 Delta Flow mufflers on a '66 Mustang. The 23-inch Flowmaster yields a tight fit. The 19-inch Flowmasters are a better fit. |