I think the relay harness is a must not because it is required for electrical safety but because the factory wiring is so marginal that the headlight output is dangerously dim.
I've got one of the old "iceshark" setups on my car (probably pretty close to what you have) and it is fantastic. I was prompted to do the upgrade because at the time I was commuting a lot after dark on an unlit 2-lane; my max safe speed increased dramatically after the upgrade
nate