Originally Posted by kakluote
what is the different between 5mm and 6mm pipes?
is it to say
5mm is designed to a low- mid speed race
and 6mm is designed to a high speed race?
You are refering to the size of the Stinger diameter (the pipe portion opened to atmosphere which expels the burned gases out).
It works as a pressure bleed valve and controls back-pressure, enhancing the port plugging efforts.
Stinger diameter affects the top and bottom end.
• Bigger = top end at the sacrifice of low end torque. More fuel consumption
• Smaller= low end at the sacrifice of high end revs. Less fuel consumption
Stinger length affects the top and bottom end.
• Shorter = top end at the sacrifice of low end torque.
• Longer = low end at the sacrifice of high end revs.
The stinger's ideal diameter and length are important to performance, but are limited and governed by most racing sanctioning bodies, therefore most comercially available pipes are designed to meet these regulations. basically the 5mm oulet is legal and the 6mm is an outlaw option.