Exhaust Cone Or 2 Into 1

Hi all I'm going to change my speed twin exhausts I have looked at several from british custom, Vance and Hines, and the cone engineering short, I also like tec parts raider 2 into 1 but what systems gives best results does a 2 into 1 decrease the power? I'm sure any of the ones I mentioned I'd be happy with tho I'm leaning towards the cone shorty or the 2 into raider anyone got either and could shed some light on the subject , thanks in advance