headlight lens query.

"lined" "bulbs" etc

I've been using the term 'lined' instead of fresnel and 'bulbs' instead of lamps because both have led to confusion when people aren't always familiar with sparks terminology

You can indeed swap fresnel for fresnel for the simple reason that siince the lens does the focussing, 'old skool' fresnel lamps utilised a symetrical reflector. What you can't do is whack a fresnel on a new style prism reflector, since you would effectively negate the ability to focus the beam.

I know of several people using high output H4s c/w a fresnel with excellent results. In all cases, a headlight should be set up so that oncoming traffic isn't blinded.