If you mean a gauge, i use the AEM UEGO, i run open headers with collectors.

7267295-nostnats2012.jpg (297 downloads)

69 Dart GTS 440 mopar .590 cam, Edelbrock heads, 3200#
best et 6.45, 106.78, 10.14, 132.88 mph, 1.47 60ft
best 60ft 1.36