Currently have the the same iron set up as you. I've been contemplating switching to the C-Tapers in an X Flex. I've only compared them in a simulator shaft vs shaft with a miz head. The C-Taper launched a little higher and was on average 3 yards longer. The shaft was much smoother than the Project X. I have a fitting a few weeks, I'll definitely be comparing the two shafts in the 712mb. I have tons of control over my ball flight with the Project X and I don't want to give that up for 3 yards a slightly smoother shaft. I would definitely find a fitter near you and compare them you can't really go wrong with either shaft.

I made the switch from Proj X 6.5's to the c-taper x-flex in my 712 cb's and i love them.  A lot more penetrating ball flight, less spin and the feel is awesome.

I made the switch about 2 months ago and have found the c-tapers to be very solid. the only complant that i have is that the c-tapers are producing a very low ball flight. not a huge problem but that shot doesn't fit my eye yet. but overall they are good shafts the frequency is matched though out the set.

Hey Bryan,

This is my 712MB shaft config:

3,4,5 irons: C-Taper Stiff

6,7,8,9 irons: C-Taper X-Stiff, soft-stepped Once

All bent 1 degree Strong, 2 degrees Flat

My swing speed with a 6 iron is 82 mph

I have a pretty aggressive and steep angle of attack with my 6,7,8 and 9 irons so this spec balances out what would be a too high ball flight. I have noticed my swing plane is pretty flat with longer irons (mainly due to the length) and so the flight would be naturally low which is why I decided on a less stiff shaft.

I was fitted for a Project X 6.5 for an AP2 set but I decided to ignore it for a specific reason. I didn't want to be fit for what was then my current swing. I knew I wanted to do a lot of work to my swing mechanics and get serious with strength and power training for golf. So I decided to get the MBs for high response irons and a stiffer shaft for a higher swing speed.

My 46, 52 and 58 Vokeys have Project X 6.5.

In my opinion, there is a huge difference between KBS C-Tapers and Project X. When I first received my set (October) My 46 degree was carrying 140 yards and my 9-iron was at 145 yards - only 5 yards less!. The Project X shaft was A LOT more 'flexy' than the C-Tapers and the distance / height etc was effortless. Several months later, and with some training, the difference is 10 yards - aiming for 15.

I guess the advice I would like to share would be to work out what you, personally, would like to achieve. If it is to fit your current swing, I would suggest noting down your current Project X 6.5 numbers (carry, swing speed, clubhead speed, angle of attack, spin rate) and comparing them to KBS C-Tapers. Obviously Trackman is the preferred but for me it was not available so I compared these 2 shafts using miz blades at Golf Galaxy's simulator. I had to find some way of comparing apples with apples and unfortunately, it wasn't available locally with 712 heads, only the Mizunos.An advance or Regional Fitter may have these available for comparison.

If your objective is to improve your swing then I suggest you call your favorite Titleist Fitter and engage him in a conversation about your objectives and it may be several conversations before you know for sure what you really want.