new to diesel

[ejs05f350]

Hi ya'll.bear with me, i've read coultless numbers of posts with conflicting views on performance enhancements. with all the info available it's a little overwhelming to process.
my rig is a basically stock 05f350 cclb w/6.0l. the only thing done soo far was adding a 4" turbo back exhaust and an airraid replacement filter for the stock intake. now my 1st question is i 've read many of you suggest leaving the stock intake and filter alone? was this a bad choice in filter replacement? if so why? seemed to gain 1/2 to 1 mpg with that change.hand clacd. or did i just misunderstand what i read in previous posts?
?#2 after all the reading about tuners i talked to matt at gearhead about tuners and he suggested going with an SCT SF3 w/custom tunes. the truck is basically used as a daily driver w/ the intention of hauling a 5th wheel soon.not looking for a hot rod, just a lil more performance and maybe upping the mpg's a little.also looking for a monitor instead of adding a slew of gauges across the dash. any suggestions?
any info would be greatly appreciated! sorry if mt questions seem redundant to the millions of other posts, but thx to all that took the time to read.