this thread is just set up for flaimbait. A search in the dyno and drag, pics and vids, or this one, could have given you all the info you needed regarding peoples setups and what engine their using.
Anyways....
people use both. the SVT 2.5L compression is not all that much larger than the 3.0L. Some people cannot fit a 3.0L into their budget, thus why they stick with the 2.5L or they just dont really see any real reason to upgrade. After all, a 2.5L holds the record for the highest hp.