What do think about larger throttlebody ? Hesco 62mm $439.95, or bore out stock to 60mm by www.jeepersandcreepers.com/ $110.00 . I'll also be boring spacer.
We bore them out all the time. Just to take out the restrictor at the bottom. That is about all you really need with a stock 4.0. For the 4.7 I built, we bored the entire TB and built a new butterfly valve.