LOL
Sorry for not being able to tell you have limited internet time. Even then, doing such upgrades to your car shouldnt be based off 1 reply from someone on the net. You should research so you know exactly what you're doing and why. Or go pay someone to do it right for you.
You're listening to a guy who just built a 331 that outpowers most 331 combos you come across. Whats your HP goal? Do you have an upgraded block?
Have fun getting a 4" downpipe to fit. Who makes that anyway? If you visit turbomustangs.com (or the turboforums.com) then you'll probably see most combo's use a 3" or 3.5" downpipe. Not saying 4" is wrong at all, but depending on your power goals, its unnecessary and gives potential headaches.
Also, i see a lot of guys run SINGLE 3/3.5" exhaust or split it to dual 2.5". Again, neither is wrong, it depends on your power goals.
Ask stopsign how long he researched to produce a package like he has. His combo didnt come from 1 person responding. You say i didnt help you? LOL You asked if you should use an x or h, i told you if you researched you'd know that
you dont need a crossover since both sides of the engine are balanced because you are running a single turbo....all of the engine pulses get smashed together by the impellar
Thats answering your question. Now did you have questions after that? If so, ask. But then again like i have said, are you in iraq modifying your mustang? Trust me when i say, research twice, and modify once. You will learn MUCH MUCH MUCH more by searching old posts then by asking questions. You'll learn stuff you didnt even think to ask. Im helping you, regardless if you see it now or later, thats if you listen!
Oh, most of all, thanks for your service in Iraq! May god be with you!!!!!!