Some other helpful mods for cooling are a larger intercooler reservoir, meziere intercooler pump, and fans.
Bigger is not always better especially for lower boost applications. I had a built 05 mustang gt with a saleen at 13lbs and it was a beast on the street. The power was instant and a blast. I then swapped over to a kenne bell 2.8 liquid cooled blower at 15lbs. Made more power but on the street it wasn't as fun. Problem was that the blower still wasnt in its efficiency range. The KB needed to be spinning at 17-18 lbs which is way too much boost for 91 octane here in CA. On 104 octane at the track it wasn't a problem.
It made most of its power up top. Don't get me wrong it felt great but the power built over the rpms unlike the saleen which came on instantly.
I don't know too much about the 6.2 with a Roush and Whipple blower so the above may not apply. Although, my buddy is making 736 whp on his gt500 with a Roush TVS running e85. It seems the newer Roush blowers are capable of some pretty good numbers.