Brighter Headlights

I have a 1991 Mustang LX 5.0 convertible. My factory headlights are nice and clear (no yellowing) and about 2 years ago I put in Sylvania bulbs. They claim they are 20% brighter than factory, which is probably correct.

Is there a brighter bulb I could go with? I do not want to do a conversion.

Thanks

Larry
 
Bulbs dim as they age, so two year old bulbs might be dimmer than they were when new

Clear headlamp lenses and upgraded wiring harness with relays might increase light output