any meter will only read at wot unless youre running open loop all the time which is stupid. at idle or part-throttle (open loop) the ecu makes constant changes to your a/f in order to keep it close to 14.7 (and save gas) thats why the gauge fluctuates. for $50 you cant go wrong, like i said before it lets you know if something isnt functioning propertly, lean. helped me diagnose a bad pump.
a wideband o2 is $200, add $300 more for the controller+display... $500 to monitor your a/f...why? unless you tune yourself (which isnt very sart anyways) its a waste.
once a setup is dynotuned there is no need to know the exact a/f...a 0-1volt narrowband meter such as the "POS Autometer" will be fine just to let you know when something goes wrong and the mixture suddently becomes lean. do you see where im coming from
who's wb controller are you using? standalone? do you still use the stock narrowband for open loop? I just bought an ems and i'm trying to figure out if i can keep the stock o2 for a while...I bought it new (oe ntk/ngk) only a couple weeks ago and want to get some use out of it. them fu*kers aint cheap.