Behold, PDRUNEN signalled from keyed 4-1000A filament:

I would expect that with 455KHz, I could use common op-amps to get the
gain up to a good level to detect the noise from the spark plug?

What if the vehicle is a diesel?

--
Gregg t3h g33k
"Ratings are for transistors....tubes have guidelines"
http://geek.scorpiorising.ca