For anything smaller then a 75mm pulley, most tuners are going to want bigger injectors and an upgraded fuel pump. For my truck, I went with a set of Deatschwerks 95lb injectors and a DW400 fuel pump plumbed into the factory fuel hat. At the same time I also added a larger idler pulley to help prevent any belt slip, a catless AFE y-pipe, and a VMP twin 67mm throttle body. The throttle body is important as the stock GT500 unit that comes with the Roush kit is out of steam by about 600whp and a 75mm pulley.
I've been through two tuners, ID Motorsports and Palm Beach Dyno. ID Motorsports is faster at the track, while PBD is a better daily driver. PBD probably makes more power as it runs more timing, but the shift strategies from ID are much more aggressive. I've started having transmission issues from the power, so I recommend you budget for an upgraded clutch kit for the 6r80 if you want to up the boost.
