5.9L Magnum Exhaust Q's

So if i was going to redo the exhaust on my 97 Ram with the 5.9L what would you do?

short headers with the 1.5 or 1 3/4 primaries? 2.25 or 2.5 outlet?

head pipes in 2.25 or 2.5"

going to run the flowmaster y pipe into a single 3" out the back.

this thing wont see 4500 and building it for tq and MPG so i was thinking the 1.5 primary and 2.25 outlet, 2.25 head pipes to the flowmaster y pipe. from there a cat delete and flowmaster delta 50.

ya or nay?