Size Does Matter
As with any exhaust system, there a certain variables that affect sound and performance. A mildly modified engine such as a 350 making 400 HP or less would never really benefit by using a 3″ exhaust. A 2 1/2″ exhaust would be more than sufficient. If you were to add nitrous and your motor is pushing 500+ hp, then maybe a 3″ exhaust would be in order.
Exhaust flow is directly proportional to power output. 400 hp is 400 hp no matter what size the engine is. Small block, big block, V-6, etc. A bigger exhaust isn’t always better.
Tailpipes tend to add more “snap” to the sound than if the mufflers dump before the rear axle or if the mufflers are mounted just behind the rear bumper. Wherever you mount your mufflers, it will have an impact on the sound. Collector mount, mid car or behind rear bumper, location does make a difference. Tailpipes make for a quieter cabin as do X-pipe and H-pipe crossovers. (Another benefit of crossovers are a slight torque increase.) Larger tubing sounds deeper but also carries more of a hollow sound. A growing number of enthusiasts are using 2 1/2″ tubing throughout their exhaust system and then stepping up to 3″ for the last 12 to 20 inches of the tailpipe to achieve a deeper sound. A couple of benefits of this are that 2 1/2″ tubing is cheaper and clearances are greater for over the axle tailpipes where space is at a premium on certain vehicles.
Here is a exhaust tubing chart showing approximate flow rates.
Chart courtesy of http://www.exhaustvideos.com/faq/how-to-calculate-muffler-size-pipe-diameter/
Nexus Mufflers are directional. They need to be installed as shown to work as designed.
Got Me Under Pressure
Common sense goes a long way when it comes to installing mufflers. Mufflers need to be fully supported in order to survive heat and vibration. Don’t weld or clamp a muffler to a pipe with no support and expect it to last. Given enough time, it will fail.
If you install a muffler at the end of a exhaust pipe with no tailpipe (IE: mufflers dumping before rear axle) a hanger bracket needs to be installed on the muffler to support it.
When installing mufflers with dual inlets and/or dual outlets, one must ensure that the center to center dimension is 5″. All Nexus mufflers with dual inlets and/or outlets have a 5″ center to center dimension. A slight variation is allowable. As an example, if you need to use a crow bar to spread the pipes apart or a clamp to pull pipes together to get them to align with the muffler, a reinforcement will be required to hold the pipes at a center to center dimension of 5″. This could be achieved with brackets welded to pipes to hold at 5″ center to center or offset pipes used to correct center to center. Excessive sideways pressure will eventually cause the muffler to fail. You want applied forces on the mufflers to remain as neutral as possible. Adequate support using rubber isolated hangers welded fore, aft, on, or a combination thereof is a must.
You want your exhaust system to “float” under the vehicle. Neutral pressure is key when installing any exhaust system.