Mini Starter .....Why?

Ok why does everyone say you need a mini starter for the swap. TTI told me and numerous others I used the original starter that came on my 04 truck 5.7 with no problems with both the 5.7 headers and the 6.1 headers. Is there a difference in factory starters or what. Just curious mine is done but I still see alot of people on here saying they have to get a mini starter.