Kyle,
Mine is a 2004 and they seem to put down more power than the 99-00 trucks as you probably know from the Lightning boards. Yours is still strong though, no doubt, but what MAF are you running? The early cars benefited from a larger one there for sure. I am assuming you are not running a stock air meter, but if you are you'd get benefit from getting a larger one. How much boost do you run? How is your A/F ratio?
As far as I know you have to fab your own intake for the DOHC swap. There is someone who has a thread on their twin turbo DOHC Lightning here:
http://www.svtperformance.com/forums...d.php?t=190281
I don't know much about it, but I think I would talk your friend out of that. Tell him to get a Kenne Bell blower along with the others usual bolt on and you can have 600-700 rwhp and 700+ rwtq for much less trouble than a twin blower setup with DOHC heads. People make a lot of power with the 2V heads, ported, with cams, with a lot less trouble than the DOHC setup. People do them, for sure, but it looks to be a pain in the ass.
Ron