Pipe Diameter

[Accord_droccA]

A common misconception is that the larger the diameter, the better the system. But, bigger isn't always better. Systems that are too large in diameter can actually hurt performance.

As a general rule, switching to a performance system that is 1/4" to 1/2" larger than stock will provide you with the best horsepower increases. To determine which pipe diameters will be best for your system, decide what RPM range your engine will operate at, most of the time. Smaller diameter pipers will produce low to mid RPM torque. Larger diameters produce mid to high RPM torque

[90AccordSiR]

Very true. I've known this for awhile but people cant grasp the concept. Thats the reason why mine is only 2.25 and its probably still a little big but i wanted everyhting to match so i had a smooth flow. One thing that you didnt mention is that when it comes to turbos on car bigger really is better and some cars boosting alot of psi can gain substantial gains from a big three inch exhaust. Thanks for sharing.

[92ex]

yeah, I wouldn't go bigger than 2.25 on a NA accord unless it's making 300hp. And for turbos, 2.5-3 is good, depending on the turbo and boost.

[Accord_droccA]

Heh Just posting this because i always see people asking about diameter sizes for the certain amount of HP they are running. STICKY please!