the tubular mani tends to be more of an equal length on the runners so you get better power through the exhaust pulse dynamics. the external gate is better for a few reasons; 1. the internal gate if it is say an 8psi gate, will start to open around 6psi and creep open slowly until you hit 8psi. the external gate with an 8psi spring wil open at 8psi ( with I am sure a margin of error for manufacturing differences, but I'd say 7.5psi worst case). this makes for faster spool up. 2. the internal is a diaphram as opposed to the spring on an external, making the external stand up to the repetative motion of open and close. result is a longer lasting gate and a more accurate gate. 3. the external gate can have boost changed by a spring, where the internal has to have the entire actuator changed. both can be adjusted through the use of a boost controller but for the cheapest route the spring is the way to go. 4. the external gate looks cool as hell.