Differences between apexi N1 and GT downpipe?

Apart from exterior what are the differences between apexi N1 and GT downpipe???? Do you think that wit a N1 exhaust does works better a N1 downpipe or a GT? Which of the 2 add more power to the car?????

N1 is what i got and i love it!!!!!!!!!

i belive that the gt is a bigger exhasut then the n1, n1 is a smaller dimater piping then the gt's..
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