Map Sensor Vac Line For Gt40/cobra Intakes

I would advise using a dedicated port for the MAP sensor and here is why. Every time some vacuum operated device like a A/C-Heater control, power brake booster or cruise control operates, it causes the vacuum to vary on that line/port. Since Speed Density depends on steady vacuum, the variations in vacuum can cause unpredictable results. The most likely result would be a sudden surge that would be hard to trace and diagnose.

A dedicated direct tap into the upper intake manifold would be the best solution. There is a lot of volume in the manifold to help maintain a steady vacuum without the sudden changes in vacuum that occur on a vacuum line shared with other devices that use vacuum to operate.

If you are clever, use can change the arrangement of the existing vacuum plumbing or have a hole drilled and tapped for a 1/4" pipe port to use for the MAP sensor.