A great new product is the Malone BigFoot canoe rack (
http://www.orsracksdirect.com/malone-bigfoot-canoe-rack-mpg104.html )for factory rack crossbars. This will eliminate the hassle of having to invest in a new roof rack system that replaces your current factory rack just to get compatible crossbars to attach a canoe rack to. With the Malone BigFoot you just connect the four L-Brackets directly to your 2006 Chevy Tahoe Z71 factory bars. You then just moun the canoe onto the L-Brackets and you have a very solid and secure solution for carrying your canoe. No worrying about the canoe sliding laterally on the bars or rocking forward and backward etc. Also you probably wont need bow and stern tie-down strapd with the canoe rack because the included heavy duty securing straps that you use with the Malone BigFoot canoe rack L-Brackets to secure the canoe down will keep it in place. If you do notice some tipping forward and backward you can always get a pair of bow & stern tie-down straps at a later date. Just place a soft cloth in between the tie-down straps and your hood and painted bumper to avoid any possible marring of the vehicle finish.