Since you have a pickup, you'll have room underhood to stack spacers. Make two 1-inch 4-holers and two 1-inch open spacers. Use one 4-hole first and see how that works, then two 4-holers. Then one open and then two. Be careful about sealing 'em up so you don't have a vacuum leak and report back with your findings. All of us would be very interested in the results of your testing and which one (or two) gave the best results that you're looking for.