I agree with the first three of the above posts. Also, Krakens already fire at about 370fps, too much higher and you'll exceed the legal limits of most fields.
As to the Trigger Master, I wouldn't for a Kraken. A Trigger Master costs somewhere around $100, you likely paid less then twice that for the whole gun. A Trigger Master is a good addition, but it isn't really neccessary untill you upgrade alot of other stuff. So I'd advise the same as Draklen, play with the gun stock for awhile. Who knows, you may not like the AK47 style and want to get something else. Also, some experience with it stock will give you an idea of what if anything you may want to upgrade in the future.