you can go without it, but the ecu will pull timing and the car will be slower, no doubt.

but the questrion is what ecu do you have? a simple fix would be a P28 because they have no knock sensor, and then you wont have to install it

but you can get a knock sensor but they are expensive and wire it up, not too hard at all, just find the ecu pinout for your ecu and run it