I have a series II VE Omega ( 3.0L SIDI )Just wondering about thedifferent types of gains on your 6.35mm manifold insulator opposed to the12mm and 25mm equivalents. Does the 25mm manifold insulator give more torque down low than a 6.35mm and if so will th

Correct, the thicker the spacer the more torque gained throughout the RPM range. The 6.35mmmanifold insulator will perform better then the 12mm and 25mm equivalents in the higher RPM range, in saying this, it is not normally important for a street car, but is handy for track/racing applications.