Any body know the stock bore size on 5.2/5.9 motor?
Fastman sells 52mm
Holley also sells a 52mm
I thought about steping up next month

 

I believe the stock TB is 47mm. I am ordering a 50mm Fastman TB for mine.

 

I can't speak for a 5.9, but on a 5.2, the stock TB is 47mm coned to 50mm. Fastman bores it straight so it is 50mm all the way. Also removes the horns on top of the TB, and replaces the hardware with all stainless parts, and puts in brass blades.