As mentioned a single tip will weigh less, it will also flow a bit better, both performance enhancements which I hope is the prime reason most would buy this. The overall weight savings is impressive but do consider that weight down low and mostly in the middle of the car is not going to make a big difference in handling, it will help in acceleration and braking more. There are other ways to spend the money to improve the car in more ways than this will do for all but the most modded cars that have done most everything else first, just the way it is.
I still really like it, not sure I will get one as would have to take off my DIY exhaust and weight it as it is a low weight and very clean flowing design and will not fit another ST easily.
I am a leading advocate of Colin Chapman's idea of adding performance by removing weight so love to see things like this come along and a far better way to spend mod dollars than on what I feel are mostly unneeded chassis braces that add weight and little else unless perhaps all other more important mods are done first.
Of course some just like the idea of a titanium exhaust, I am in that camp as well, and they can sound so sexy!!!
(except one I heard on a buddies new M3 back in 2003, it sounded so horrible he had to take it off and it cost a ton of money