I am hooking up a new 3 gauge set, oil, temp & ampmeter. where is the best places to run the 2 wires for hook up. followed the instructions and the car wouldn't start??? they said to install it in line at the horn relay. the were not clear after that. this is a generic gauge set made in asia so lots of key words were left out of the destructions. the oil and temp were easy enough and work fine. they rcommend 10-12 ga wire. is used 10- is that to thick?