hi, first off, please forgive any ignorance or stupidity... i am indeed kind of green when it comes to bike knowledge, but i'm attempting to get better....

OK
i have a redline 925 and am running the stock gearing of 42 X 16

can somebody recommend perhaps the 'next logical step' in gearing for getting more speed out of the bike, but not necessarily something that is going to give me a stroke going up hills? i'm pretty much OK on hills with this gearing (depending on the day and my mood!) but on the flats i'd like to average more like 25mph than 18-22mph.