I just happen to have a Walbro 391 laying around. I'll probably be making a kit to install it soon. I've read the 392 puts out about 30% more than the 391, but I haven't found any info on how much HP either will support. I know I'm not anywhere near the limits of either, but just in case I hit the lotto and have extra $$$ laying around, I'd like to know what the limits are. Thanks.

 

I don't know about the 391, but there's a guy on TDR who's running the 392 @ 893 HP.

 

I dont have a clue on have much power im making cuz I dont know what injectors are in the truck, but I think they are kinda big. But My walbro 392 is at aprox. 19psi at idle, and I can get it just below 10psi at WOT. Bret