Originally Posted by 240M3SRT

You simply watch the gauge as you drive. Actually its safer to keep your eyes on the road and have a friend watch the gauge as you do a run or two.

Installing an a/f gauge is easy. Have an o2 bung welded into your exhaust for the sensor, preferably before the cat. You route the wires into the cabin and get power from the fuse box. On our cars there happens to be a convienient pre-existing hole by the brake master cylinder, and the fuse box is on the driver side of the dash.

After my pulley and intake were installed my car ran very lean up top. The tune fixed that until i did my intake manifold mod, then it ran lean again. The only way i could possibly know this is from the a/f gauge. Its amazing to me more people here dont run them.


In fact my main reason for the tune was to actually richen my a/f so my car is always safe, not the added power...but thats nice too. Leaner is meaner but only until the ring lands crack.