Twin Tec Ignition ModuleTwinTec 1006 ignition BT90 94 XL90 93 This external plug in ignition module offers ease. Just remove the OEM ignition module, and replace it with the low profile billet aluminum Twin Tec module. This gives you four rotary switches to select either Single or Dual Fire application, two advance curve families with adjustable advance slope to accommodate for stock to highly modified engines, adjust timing advance, and set the RPM limit in 100 RPM steps.