I just finally finished up a v3.0 for my car. My original plans were to isolate the tach input to another board to help isolate noise within the v3.0 board. I have always had 2 theories on this issue:
V3.0 board has a flaw or is more succeptible to noise, Cars with tach noise have issues witht he sensors degrading and the v3.0 can pick it up.
I built the v3.0 in its factory design (sort to speak) and set it up to run just like the v2.2. Not a single spike!
Here is my setup V3.0 running tandem with Factory ECU Spark "pullup output" to Crane Ignition box NO IAC Idle 800-900 Factory crank receives power and ground from the factory ECU Factory TPS " " " " " " " " NO SPIKES
no special noise supression wiring only GXL harnesses i sell routed with factory harnesses.
I will drive this thing a bit more this fall to see if conditions change.