The whole and single reason I went the path of factory Pro, is they are the easest to set up. (The kit cost is a bit more )
Follow there recommendations to the letter.
My local dyno shop, turned me in that direction(factory pro)
As Deano says dyno time is money. Factory pro kits are mostly spot on with thier remmendation for settings, where as Dyno jets and Ivans can be a bit of a F*#* around.
With Project REX I followed the instructions for the stage 3 kit to the letter, and I have not touched it since, perfect in ever range, no faultering no flat spots, just perfect. Not bad, really, carb settings right first time. But Deano says this is pretty normal for factory Pro.