So, you got replacement software for your stock ECU? I think this is the way to go as it maintains closed-loop operation. I don't think piggyback ECU's are such a hot idea, with perhaps the exception of the one that TRD delivers with their blower - I think it's pretty passive.

They change fuel amounts and ignition timing (there's your ping.) It really comes out with breathing and fuel delivery improvements.

There are better filters than K&N, there were when I was racing, I don't know what's out now. I'd look for something that doesn't pass light and won't oil your intake.