That makes sense. My bore is 4.195. 454 is 4.250, 350 and 4.3 are 4.00, so probably the 454 would be best?

I assume the advantage of the untuned knock sensor is that it can be tuned for my bore, right? Are they "alot" more money? I think I paid $25 for my knock sensor so if a better untuned senor and knock filter is $50, that's worth it to me. but if an untuned knock sensor and knock filter are $200, I will run a 454 sensor....