I have changed the weight chip for both my 913 D2 and my 915 D2. The config of both my drivers with the red 9 gram weight was D3, so I swapped out the red for the green 7 gram weight on both to get to a D2 swing weight. I also have a 5 gram weight (white) for my 915 that I tied for a couple rounds. It didn't seem to make any difference in feel, ball flight, etc... so I went back to the 7 gram weight. I am toying with the idea of swapping out the 11 gram (red) weight in my 816 H1 for the 9 gram weight to see how I like the slightly lighter swing weight. I have not changed any of the weights in my Fwys or older hybrids. I did not buy the weight kits for my drivers, I just bought individual weights through PGA Tour Superstore.

Ball flight !!

Changing weights is more of a fine tune. The heavier weight in the back will increase forgiveness and launch angle as well as spin rate

I honestly can not stress enough the value in getting fit for your clubs from a certified Titleist fitter. Is it cheap? No. But... I think it's totally worth it. They will be able to definitively tell you weather or not you need to mess with the weights as well as optimize your ball flight.

The only thing that will change will be the swingweight of the club by changing the weight in the 915 and 816 series....swingweight refers to the lightness or heaviness of the club as you swing it.

Thanks for the information. I was fitted by my local Titleist Rep for the clubs, shafts etc etc I currently have including my 716 irons but the subject never came up about weights. I just got curious the other day when I was cleaning my clubs thinking what effect do they have if I changed them. Now I know, thanks again everyone