Before I move this to the Windsor Power Forum...
FWIW, I converted my '87 to mass air with used/boneyard parts, and I can't tell you how much better it is now in every way. Well, mebbe I can. I ran a half-second FASTER this year since the conversion! That's the only mod I did since last fall that'd make any difference. Going from 14.7 to 14.3 (with an AOD & completely stock motor) was nice.
Now my mission (with some minor bolt-ons) is to break that damn 14-sec barrier. Wish me luck!!!
I'm not trying to discourage you, but I'd seriously look for another engine, preferrably an '87-'91. '92+ have cast (okay, hypereutectic) pistons, which suck. The '86s are infamous in the 5.0 community for offering basically nothing in performance, reasons too numerous to list.
As for an intake, the best bang-for-the-buck is still the Cobra. IMHO, fiddling with an Exploder intake is too much trouble (I know some will disagree, but there it is: my opinion
).
Mass air meters are pretty easy, you just have to make sure that it's calibrated/matched to the injectors. Apparently C&L is the one to beat, plus it uses your stock MAF element. MM&FF did a test on that and a Pro-Flo, and the C&L beat it across the board. 75mm should be considered a minimum for any performance application.
You need these mods to compliment each other though, and I think you're throwing money at a longblock that really needs some help, particularly the heads & pistons.
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Capri306, Moderator, The Mustang Works Online
1979 Mercury Capri, 5.0L -- C4 -- 2.73
1987 Mustang LX Notch