Read your other thread
http://forums.sv650.org/viewtopic.php?t=32219
Dr Squid points out that one tooth less on the front is roughly equivelent to 3 teeth up on the back.
So if you do both sprockets then you will get something roughly equivilent to a 50 tooth rear, which would give you alot more oomph, but could drastically affect your top speed (though probably won't bring it below 110mph or so)
I don't believe a 50 tooth rear is available, so changing both would be the way to go to get that much, though how necessary it is I'm dubious of.
I only took mine up to a 46 rear with a standard front, because I needed to be able to cruise at high speed without revving the hell out of the engine.