turbo upgrades?

2nd gen mani will spool slightly faster and have a great sound, also noted lower egts. If you plan on upgrading to twins you'll already have the mani for it.
My vote is a cheap used 3rd gen stock manifold and a 66/74/14 non gated. Cheap and easy

Spool and lower egts are a plus... not too worried about sound.. t3 or t4? Mind elaborating why you suggest nongated? Ease of installation?

3rd gen manifold the cold air intake is the same, the intercooler tube will be the same, as well as exhaust. With the 2nd gen u need to modify all of those. Not a big deal, just not a simple bolt and go. I had the 2nd gen setup on the 03 and it was nice, i also bought everything all setup though.
I'm not a fan of internal gates and pluming an exgate a mild upgraded daily driver isn't needed. I've had several reccomend non gated 66/74/14 for the 6.7.
E.D. builds the"better bullet" that gets good reviews.
if its a stock 3rd gen mani then u have to go t-3, other wise i'd for sure go t-4 for flow.