FAST OR SDS ENGINE MANAGEMENT

DOES ANYBODY KNOW WHAT SYSTEM IS BETTER FAST OR SDS?? I HAVE PURCHASED A FAST MANAGEMENT SYSTEM A WHILE AGO AND HAVING SOME PROBLEMS WITH INSTALL ON MY 98 COBRA. FAST SENT ME DIRECTIONS BUT THEY ARE NOT TO GOOD TO SAY THE LEAST. SDS DOES NOT NEED A LAPTOP BUT COME WITH A HANDHELD SCREEN THAT U DO ALL YR PROGRAMMING WITH. SDS SEEMS VERY SIMPLE AND EASY TO INSTALL BUT I DONT KNOW IF THERE IS A DIFFERENCE BETWEEN THEM. PLZ HELP!!!!!!!!!! THANKS. ROB.