I have decided to get my own tuner so I don't have to keep asking to borrow my friends. I want this in the car at all times and I have an extra bung already welded into the dat delete pipe. Now how do I get that big connector to pass thru the firewall? where did you pass yours thru? Seems like the best place is under the pass. seat where the stock 02 goes.

 

Actually, IMHO the connector is always too big. I went to radio shack and got some of those quick disconnect connectors, I cut the O2 wire (and knock sensor wire) and soldered the connectors on. Then you tape them with something around the wire in a way they're not all next to one another so they can go through the firewall hole and then you can, of course, push the whole thing through the hole (I used the one on the passenger side, behind the glove box).
What I originally wanted is get a nice small molex connector so it's even quicker to take the whole thing apart but couldn't find anything in the local stores and was too lazy to google (I did but didn't find anything I liked so I quit ).

btw. I would recommend connecting the wideband O2 very close to O2 housing, not the test pipe (should basically come on a first knee of a downpipe).

 

there is also a hole in the floor up by the firewall on the passenger side of the driveshaft hump. It comes up under the shift console if I remember correctly. you can stash the tuner in the glove box if it will fit and hide the wires easy. I had a bung put in my downpipe, just turned out that is where we put it.

the o2 sensor will fit down through the hole, not the connector.

guess I should say I am thinking of an o2 sensor, don't know what a tuner setup looks like.

 

Oh, few more things... I took the insulated connectors and I cut the wire very close to the connector that goes into tuner so that quick-connects are in car and not outside exposed to weather. I did the same for the permanent power wires... they tell you to hard wire it and I didn't so I can quickly remove it if needed. I also put 2 quick disconnects and since I own one of those car inverters (so I can plug in my laptop in the cigarette lighter) I soldered the 2 quick-disconnects to the inverter
I'd make pics but I'm not sure where my Tuner box is since I just moved and I thought I'll have to sell my car so I removed the whole setup from the car. If I find it I'll show ya..

 

Both Tuner and Bosch sensor I have come with rediculously big connectors which you can't push through any of the holes

 

but won't the sensor drop through the hole?

 

Everything is possible
Sensor will, but you only have about 5" of wire after it...

 

If I remember correctly I was able to get the sensor through the grommet on the passenger side behind the glove box. You would not believe how many wires that I have been able to get through that hole. I tap that hole more than my wife's.

 

My evo's grommet hole was too small to pass the connector for the Tuner through it (or the sensor)

HOWEVER, there is a reason, the tuner has two O2 sensor options, the bosch o2 sensor and knock sensor, or the NGK sensor.. My tuner pro came with a bosch sensor, and the connectors on either end of the cable were way too big to fit through the grommet hole...