Some people like me think that the standard topbox wobbles, some dont, but this is how i fixed my box to my bike, i did drill the fixings a little wider through the cheker plate Alloy for better stability.
The bike is black (the correct colour) and has done now 1100 miles in 2 months, the second bike in the pictures is the brand new Honda Fireblade i won in 2008 in a nationwide competition organised by Honda to launch this new Blade, i won it and rode it for 275 miles then sold it for £8k cash, to damm small for me.
Alan
thats a good idear, but have just fitted my top box on the original rack, and yes it dose wobble abit when firm pressure is applied, but the rack its self seems secure. so I thought its the racks arms that needed the extra support, I can see the alloy bracket you have fitted but have you fitted the alloy bracket to where the original rack was secured and just spaced the securing nuts further apart, the reason am asking is the most I could space the bolts more is approx inch, and I original dismissed that, thinking it would not make much difference. however it seem to work for you! so may have a re-think!