Congrats on the "L" purchase!
They are very nice trucks, I would have one except I have to haul 2 kids, so I got the HD (next best thing)

Anyways...in stock form they put out 8lbs...so a 6lb pulley will put you right at 14 lbs boost total.

so if you decide to spray a little, make sure you get the tune right on the $$, I mean take it to a dyno with wideband O2 capabilities, some dyno places can also "Tune" your chip to make any adjustments needed based on the dyno results.

And whatever you do....DONT do any kickdowns!....cruising in third and then mash the throttle so the tranny kicksdown into 2nd, I have heard this is one of the main reason for broken rods!

Good luck with it!!!
And be careful!