The size of tubing used in an exhaust system is a critical item to consider. Tubing diameter 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 mildstreet applications (V8 dual exhaust) use 2.00” through 2.25” tubing, and modified street applications (V8 dual exhaust) will generally use 2.25” or 2.50” tubing. Very rarely will 3.00” tubing be used for (dual exhaust) street applications. In general, the following guidelines should be applied for street applications. Remember, these are general guidelines only and specialized applications may differ somewhat. For more specific information please contact Flowmasters tech department.

Tubing Size	Dual Exhaust	Single Exhaust
2.00”	up to 200 HP	up to 100 HP
2.25”	up to 325 HP	up to 160 HP
2.50”	up to 500 HP	up to 250 HP
3.00”	up to 600 HP	up to 300 HP