In all fairness the speakers aint that bad it the headunit that needs to be changed first you wouldnt believe the difference a decent headunit makes
Unless you have done already in which case 16.5" speakers by any one from kenwood to jl audio would suffice mate.
There is a lot of info in the 'sticky threads' at the top. The Honda speaker upgrades are not well thought of. However, there are many aftermarket options, which you will likely need speaker rings/adapters as the standard speakers are quite shallow.
Like Wardy says, the stock ones are actually ok. It's the HU that really lets things down and a speaker upgrade won't help much at all. If it hasn't already, the CD player in the stock HU will stop working at some point anyway, so you may as well swap it now