I use my ipad 2 for work, want it to alert me when there is incoming mail, but the sound is so short and so small, hardly can notice, is it possible to change to something else ?

thanks.

No by default. Stick with it until iOS 5. Or JB it for now to increase volume or tweak for diff sound.

if i JB it means i need to use other app to give me that flexibility ?

If u jb it, u can tweak the mail tone. Of course use back the stock mail app.