does a wideband gauge etc need to be wired into oem ecu :S
 

does the wideband have to be wired into the oem ecu??

thought it was just

stock lambda in cat

lambda from wideband into lower cat and just wire the gauge from a power source in the car??

No it can be run as standalone sensor and gauge,it can be run in place of the stock narrowband and run in simulation mode for logging if you have the correct wideband kit.
I just run mine as a standalone.

i just want to fit the lambda from the gauge in the 2nd spare port i have on my cat and keep my oem lambda

i take it wiring this into the ecu replaces the oem lambda and make its only run 1 sensor???

Yes you don't need to run the oem narrowband if you want to run a wideband and switch to simulation when not tuning.
But if you just want to run the gauge all the time then best running it as a standalone,also if you place the gauge after the cat it won't be accurate.

Edit:some cars have the oem sensor in the collector which wouldn't be ideal as I beleive it will kill the wideband pretty quick

My OEM lambda is in the headers (95 wrx) and my wideband is in the downpipe just after the turbo ( been running there 3 yrs now )