I purchased a 915D2 on release date with a stock diamana in it. My local pro shop had a YS-6 for sale brand new had a sale before Christmas I picked it up at a bargain and tried it more out of curiosity than anything else. Well I have played three rounds with it and I have gained an average of ten yards while splitting the fairways right down the middle. I love it and can't wait for dry green fairways to see just what it will do. Hope this helps

Dwayne,  Good to know the YS6 is working for you in the 915.  I'm the type of guy who doesn't do a lot of changing of equipment.  The YS6 had been really good to me.  Hopefully the YS6 & 915 combination works for me.  

I also have a YS6 in my 910 driver and FWs.  I have not bought a 915 yet, but I do have a 913 and have tried the YS6 in it with good results.  When I purchased my 913 I was fitted with the Graphite Design G 60.   The YS6 is a very good shaft, but to me the G 60 out-performs it.  As I always suggest though, go through the fitting process and find the shaft/head combination that works best for you.

Best of luck with finding the right shaft/head combo for you.

Hello Barry, as you suggested, I do plan on going through the complete fitting process.  I will have to look into the G 60.  I will report in with what I end up with.