gear shifting without clutch
you can its difficult but ya u can. just pop it out of gear apply pressure to the stick for the next gear and when the rpms start coming down it should pop in. down shifting is really difficult u got rev it up and then when the rpm's start falling again same procedure. but alot of higher end race cars with manual trans will put straight cut gears in and it makes it alot easier to shift without a clutch it saves on the shift times but they wear extremely fast, as would a regular tranny.
Josh is right. Every transmission has a sweet spot in which you can shift when the rpm's are right. Depends on the transmission and gearing ratio on where that sweet spot is. You will just have to feel for it.