Increased heat generation is entirely negligible, and won't effect the lifespan or function of your headlight lenses or housings. 2. It's our understanding that the bulbs themselves don't effect the aim of your headlights, and that headlight beam direction is a function of headlight itself, not the bulb. That being said, we're not all that familiar with the Japanese-spec Mustangs or right-hand drive cars in general. Your best bet may be to contact a local shop to verify the beam aim functionality of your car's headlights.