Absolutely, your wideband ought to go in front of the cat. I'd put it very near where the stock bung is mounted. Be sure to mount it such that it angles slightly downward, for reasons I stated above. Wicky, there's no need for the second sensor with the EMS -- no benefit from running one, other than curiosity about how air/fuel ratios change as a function of where in the stream the measurement is taken.

 

can the wideband sensor simply replace the narrow band or will that make the stock computer cranky?

 

Cranky. Very cranky. The voltages are completely wrong, and it won't know how to handle the signal. Nice thought. When I switched to the EMS, I ditched the rear sensor and used the front bung(hole -- with TP) for the wideband. But that only works, obviously, with an aftermarket ECU.

 

i just don't want to spring for over $1k for an ems right after dropping serious money on a super. down the road definately. hmm... i wonder if there are any used EMSs around.

 

there's really no need for the wideband, if you aren't going to tune the motor with an EMS or something similar, the sensor alone won't help anything, and as cbender said, with the stock ECU you're just asking for a headache.....

 

Well, if you're using a VAFC to tweak the stock ECU's air/fuel values, I think a wideband would be useful but probably not necessary. But if money's tight, Wicky's right.

 

You actually have 2 good options.

1 you could replace the 1st o2(stock) with the wideband o2 and use the narrow outut from the wideband to connect to the factory computer. this way you have the best of both worlds, kinda. my bosch lsu doesnot fit the stock bung, but the ntk might work.

2 you could add a bung just before the cat. this is the the best way in my opnion. Easy removal in the future and no changes to the stock setup.

3 If you have a test pipe you should place the bung inbetween the 1 and 2nd o2.

Many people feel the wbo2 should be as close as possible to the exhaust manifold, but at full throttle the heat will burn out the wbo2 as well as the exhaust is flowing at such a high speed you are talking .0000mil sec difference in reading times.