Contour Enthusiasts Group Archives Forums Modifications Duratec Performance exhaust is smaller better

I've been reading and researching this site on and off since the day i bought my Mercury Mystique 2000.I,ve learned alot. My main question pertains to the length of the resonator and muffler either by Flowmaster or Magnaflow. The original part numbers for the magnaflow #10435 and #11225 -i notice are the favorite among the site. The 11225 being the oval o/c 4 x 9 measuring 20" nip to nip - 14" to body edge . The #10435 being the resonator 2.25 c/c 28" nip to nip - 22" to body edge and a 2.5 core.Now with these measurements in consideration im wondering is there a major factor i should worry about with going with a smaller inner core and/or shorter length. I want to switch the above mentioned with the Magnaflow stainless resonator part #14415 with a 2.5 core or #14445 which has a 2" core.Both are also shorter. The muffler by Magnaflow i was also considering is the #14362 4 x 9 oval body o/c 17" nip to nip - 11" to body edge. As for the Flow master muffler #942442 4" x 9.75 x 13 - 19" overall length. Can anyone help out with opinions and/or inform me on the differences ralating to the dimensions in core size, etc. One last thing, is the 2.25 in/out diameter accurate for the 2.5 V6.........not to much is it. 2.5 is too big , i believe there really is'nt any addition benefit.