big headers

is there a disadvantage in have header that are too big for your motor . like the kooks headers that are 1 7/8" into 3.5" collectors or are they just a waste of money to pay for the extra size. my car is mostely stock right now but i want to do a cam and head swap maybe this winter and i just wonder if that would be to big and hurt the motor. i would put true duals with a xpipe also

go with the kooks if you can afford it.
big headers just help your car breathe more, which if you do a big h/c swap, will help out a lot