Al9

hi all,just purchased a 02 wrx uk model,it has a 3" t304 stainless steel exhaust(free flow), and i have today got a decat for it,so the whole original system has been replaced.want to know how much difference has this made to the power(bhp) and the torque,i do feel a difference or is it just in my head! also since having it done, i have developed a small leak(water) from a rubber pipe(about 8" long) where can i get the rubber pipe from would halfords etc have a pipe that i can cut to size as it looks straight forward to do. thanks