Hi Frank, When we offer a shaft, it has undergone an extensive shaft testing protocol for both durability and playability to make sure that it will work in our heads. At this time, our stock LTD Red 50 is actually 47 grams in an A flex and 48 grams in the R flex. More often than not, names (when they include numbers) are not the actual weight of a shaft.
There is no industry standard for flexes so one company's R flex may be another company's A flex. If you like something lighter than 47 grams, we would recommend that you try the L flex and see the ball flight. We can build it to standard men's length and have done that for players.
The other note is that even though a shaft may weigh more, it may swingweight less due to the balance of the weight along that shaft. With today's adjustability in heads, you can make the swingweight (and head) feel lighter by changing out the weight. A good club fitter will be able to dial you in when the new TS drivers are launched. If you have signed up for stay up to speed: www.titleist.com/.../golf-drivers, you will be one of the first to be notified once we start the TS fittings.