Stock wiring is barely enough for 55 watt bulbs. Due to this when wiring is bit old it becomes worse and even 100 watt one does not work good. it becomes hot even on 55 watt bulbs. anyway I have used 90/100 watt ones and they work ok. but better would be to use good brand bulbs in 55 watts. this way reflectors, wiring and alternator will be happy. it is good to change bulbs after 2-3 years. All connectors should be clean. if there are joints, solder them. replace wires if in bad condition.
relay with thick wires will give very good light, even with 55 watts. but you need a electrician who can wire like a pro. and must use fuse where wire come out from battery.