I think I need one... I keep messing around with things and throwing the mixer out of tune.
I was looking at this one, because it is kinda cheap.
http://store.summitracing.com/partdetai ... toview=sku
However, it might not be wideband. And it only offers output of what is happening in real time. Basically it's a Gage. But I imagine I could tune by it by just watching what it does. Unless it is narrowband, then there's little point.
There's this one:
http://store.summitracing.com/partdetai ... ew=1&N=700+
But it's $600 for it with a RPM converter so I can log a meaningful curve. Obviously it's not even the same league of product as the K&N one. It'd probably be a better investment in the long term.