I have never tried the magnaflow, nor heard one in person. So I can't really tell you if there is much difference between it and the MBRP. I do know that you will get a slightly deeper sound with the 5" compared to the 4". But if you are talking stacks, that's a whole different ball game.
I am running the 5" MBRP on mine, I personally love it. I do not like the vents (consmetic wise)on the tail pc, but I do understand their reasoning for putting them there, so..... Other than that, love it.
Good luck with your choice.
