There aren't a lot of one-size-fits-all answers to the questions being asked here. The biggest single piece of making a turbo set up work the way you want it to is having someone that knows what they're doing help you with sizing. And that's never done with the junkyard set ups -- a lot of folks out there think turbos are like boxer shorts -- just grab a pair and go. If you want a nice set up that with minimal lag, quick spool, and lots of torque down low it takes a bit of design, or lucky guessing.
Besides Paul -- most any of the twin set ups out there are more than capable of causing that stock block to pull a Paris Hilton on you --- laying open with a big split right down the middle. If you're serious about twin digit boost with turbos or superchargers a block upgrade is a must for longevity.
Mr yount I havent seen you post here in the longest ...
Paul listen to him . I would consider his and hissin50 to have the best advice thats relible ... Also paul you want a good build up on jy turbo kits let me know i have some good reading for my project .
5.0 computers don't always enjoy turbos, and they can easily put the car into the DFI zone, that's no walk in the park.
But worst of all the fittment is a serious issue. There's very few kits that completely fit perfect without having to take the car to an expert to get finished, i think helion is one of the high end kits that does fit, but it's gonna cost you.
If a turbo was just a slap it in and drive on a mustang, more people would have a turbo than a supercharger.
I make no argument on power, because i see first hand how powerful turbo mustangs are, but i also see the cars all land up at kooks to be done right, and you aren't leaving there until you are in debt.
Cars are all slightly different, companies use mach-up cars and engines to build the kits, unfortunately sometimes they aren't perfectly the same are a customers car, thus, things don't always fit.
Where's if there is no real piping on a supercharger, just bolt it up, make a few fuel adjustments and you are off.
Goto one of these turbo mustang sites, see how long everyones cars are down for turbos, i bet some are down for weeks even months.
Turbo street 5.0's are for people that take this hobby extremely serious, and have probably been through a couple of other setups, they are not a rookie mod.
Not sure i've ever seen a guy with a turbo 5.0 as his DD. But there's dozens of guys that do it with Supercharger.