Should i try loose abit more weight for boxing read question :D?

im pretty keen to have a fight now i been doing it for about 4 months now,im 18 6.2ft tall 90kg but my mate that's been doing boxing for about 3 years says i should try loose 5 more kg and i would have a much easier time vsing people that are 80-85kg do you think i should try loose 5 more kg or just go sign up for the fight fortnight from now as 90kg???