Gunslinger,
I would say some of the advantages of the "T" would be weight of the tanks, allong with this would be the weight of the fuel, the "T" will pick up more fuel from the tank so you don't need to carry as much. Also in holding less fuel you won't store as much in the tanks between races.
They are also nice when running a bypass regulater.
Is the boat going to be a drag race only deal? If so you can get away with a bullet tank which is all the better for the above reasons. If you are going to also use as a lake boat, Put a bullet in with a valve to switch tank's or IMCO can build you a "T" tank which can hold alot of fuel. I just ordered a tank with a special sump. It is going to hold 15 gal. for my sprint boat.
Good luck
Morg.