Originally Posted by SS_Firehawk

Just to clarify to everyone who thinks loss of back pressure means loss of low end tq. Your wrong. Because you have an enormous tube for an exhaust, it reduces the velocity of the exhaust leaving the motor. The domino effect is it reduces the scavenging effect or more simplistically, a vacuum effect of the exhaust assisting in pulling the gasses out of your cylinder. At low rpm, it's crucial in developing low end tq. The higher rpm you move up the power band, the less effect it will have because now the exhaust velocity is up to an acceptable point to continue scavenging. Exhaust size is critical to the amount of air your trying to move. A 3" dual exhaust will really only benefit you of your pushing 650-700hp at the crank or higher. 2.5" exhausts are perfectly sized for our motors until you start pushing some serious power.