DodgeTalk Forum banner

1 - 1 of 1 Posts

54 Posts
Discussion Starter #1
How to Design a Custom Exhaust System

For customers who are considering designing a custom exhaust system for their vehicle, we have listed some of the basic things to keep in mind when designing a true dual system. Most of these points can also be applied to a single system.

Pipe Size:
The size of tubing used in an exhaust system is as important as selecting the right muffler. Your tubing diameter choice will affect the sound level and performance characteristics of the muffler, but keep in mind that bigger is not always better. Using tubing that is too large can actually hinder exhaust scavenging by slowing the velocity of exhaust pulses in the tubing. As a rule, most stock street applications running dual exhaust use 2.00” through 2.25” tubing, and modified street applications (dual exhaust) will generally use 2.25” or 2.50” tubing. Very rarely will 3.00” tubing be used in dual exhaust street applications.

In general, the following guidelines should be applied for street applications:

Single Pipe Diameter / Horsepower

2.50" / 150-200
3.00" / 200-250
3.50" / 250-350
4.00" / 350-425
4.50" / 425-500
5.00" / 500 and up

Dual Pipe Diameter / Horsepower

2.50" / up to 400
3.00" / up to 500
3.50" / up to 700
4.00" / up to 850
4.50" / up to 1,000

Balance Pipe(H-pipes and X-pipes):
Flowmaster strongly recommends using a crossover tube, otherwise known as an “H” pipe or balance pipe on all true dual exhaust systems. The crossover pipe equalizes the exhaust pulses and allows the sounds waves to communicate between both banks of the engine. Not only does this usually improve torque in the low to mid rpm range, it also creates a deeper mellower tone both inside and outside of the vehicle and helps eliminate “back-rap” on deceleration.

Flowmaster has performed extensive testing and determined that the “H” and “X” pipes deliver no significant difference in performance, but do affect tone, the “X” pipe giving off a higher pitched tone. Flowmaster Scavenger “X” pipes however, do increase torque through use of their patented D-Port technology and retain the deep Flowmaster muffler tone desired by most performance enthusiasts.

Muffler Selection:
The sound of your exhaust is much like music; we all have different preferences so it’s important that the system be “tuned” to what you like. With the Flowmaster family of products we can help accomplish this by answering the questions below. This approach will allow you to choose the best product to suit your needs and expectations.

1. What is the vehicle year, make, and model?
2. Which engine do you have or how much horsepower does it produce?
3. What is the vehicle used for? (i.e.: daily driver, race, towing etc.)
4. Preferred sound levels (interior and exterior?)
5. How are the space requirements?
6. Would you like a complete exhaust system or universal pipe kit if available? Single or dual outlet?

Header Collector Ball Flange Kits:
The Flowmaster Ball Flange Kit takes the place of messy three bolt flange type connections and allows for a leak free and gasket free ball flange type connection. All kits are 16ga aluminized tubing and are sold in pairs.

System Hangers:
Adequate hangers should be used to properly support the system. Flowmaster uses OE style hangers in all systems.

Resonators are designed to be used in conjunction with your mufflers for improved sound reduction. Resonators will help to eliminate interior resonance.

Stainless Tips/ Exit Location:
Flowmaster highly recommends running a minimum of 12” tailpipe after the muffler. This will not only greatly help in sound control, it will also provide an increase in exhaust efficiency (more power). Running tailpipes out from under the car in street applications will also direct the potentially harmful exhaust fumes away from the vehicle, as well as minimize the sound transmitted into the cab area of the vehicle.
Flowmaster's line of Stainless Steel Exhaust Tips are a great way to let people know that you have Flowmasters under your ride! They come in a variety of styles from brushed to polished and will greatly enhance the look of your vehicle!

If you have further questions regarding any of our products, please call (707) 544-4761 or visit our website,
1 - 1 of 1 Posts