The next time you go to Bass Pro, please talk to someone else. The point of using a tapered leader is to get the butt end of the leader where it connects to the fly line to be of nearly equal stiffness as the fly line. If not, as the stiffer fly line is rolling over on the cast it will create a hinge and the loop will not roll over correctly.
There are two possible problems this can cause: One- The hinging effect WILL bring the fly closer to the line it is moving past, and this increases the chances of tangling. Two- That same hinging effect means that power from the cast rolling over greatly diminishes, and could keep the fly from turning over completely. (to be honest, with a weighted wooly bugger this second effect probably won't come into play, becuase the inertia of the weighted fly will help it finish its flight. If you were fishing poppers or bulky floating flies, it can definitely come into play though.)
If you want to get around those two potential problems, you could make your own leaders with 3 sizes of mono. For a 6wt rod, I would use 4' of 25 lb, 1.5' of 15 lb, and use 8 lb for your tippet, 2-3'. Yes, I meant to say 8 lb. A 6wt rod that is broken by tippet over 4 lbs is a sad stick. You could possibly break a 6wt with 10 lb, but you would have to know exactly how to abuse it to make this happen.
I would recommend using the loop-to-loop method for joining your leader to your line. Loop-to-Loop Connection
Use a short piece of that 25 lb line and make a loop that will stay permanently in place on your fly line, so that you are not having to cut off fly line each time you change leaders. This is the ideal knot to join that section to your fly line: Fly Fishing Info Center - Nail Knot - Leader to Fly Line
This is the ideal knot for making the loop: Fly Fishing Info Center - Perfection Loop
But this one will work just fine also: Fly Fishing Info Center - Surgeon's End Loop Knot
but try to keep it small. (dime to raisin sized)