Remember to figure out what gears you want to run before you start cutting your chain. Even a small change like going from 40 to 42 teeth will move the wheel in some. I bought about four master links at once and I started at +6" and I could not hold traction out here in the streets of Las Vegas even with a Shinko stealth tire on the back (all of this was last year before I went turbo). Also with 6" stretch you loose wheel clearance because the center of the tire is now at the end of your fender. I could not ride two up stetched at 6", when I did try, the first bump in the road folded the license plate above the wheel.
I replaced the master link, cut off some more chain links tried again at 5". Traction was much better but still slippery on the city streets and highway. 4.5" stretch is what works well for me and it definitely helps at the dragstrip. May not be the best dragstrip setup length but I do 95% of my riding off the dragstrip. I did have to go with a tiger tail to get more clearance above the tire. I would up with a 2" rear and about .75" drop in the front to get the bike to set rite. Remember when you go with extensions it really raises the seat height because of the angle is the swingarm. So to make the bike look rite you have to lower the rear suspension. When you lower the rear then to prevent the chopper look you need to lower the front slightly.
The changes will definitely help but think it thru first because you start creating other issues at the same time.