Im considering buying a A/F gauge for my S4. I was just curious on how easy they were to install? How many wires, where do they go to?

It's very easy: For most gauges 1 wire is ground, 1 is for +12V switched, and 1 is for the O2 sensor signal.

so i have to split the o2 signal wire in 2?

Just tap into it. A tap splice connector will do ok.

The O2 sensor is usually sheilded... So you a simple tap won't work. (I found this out the hardway).



I have a O2 gauge in my Haltech powered Zuk, They are a little slow to respond. Something I am considering is a wideband O2 Sensor UEGO like the one used in the Honda Civic.



Build your own wideband



This one will actually show you the A/F ratio in realtime.

You can tap into the wire at the ECU.

the ecu is under the passenger's footplace right? im probable gonna tap it there...any 12v switched power around the dashboard?

Yeah, you can find out which ECU wire it is in the manuals at http://www.fc3s.org . You can use a voltmeter to find +12V switched. I usually get it near the ignition switch. You'll want a +12V source that comes on when the key is in the on psition, not acc.