Bang-for-your-buck the bolt-on turbos will go a LONG ways. If he's only looking at 50-trims or the green, a 68hta would be what I would recommend.
http://store.forcedperformance.net/m...Code=DSM-Turbo
This would let you use all of the stock oil and coolant lines and you'll see 50-trim numbers.
Now an interesting twist to this is that FP is now making the green with the HTA wheel in it (by the looks of the pics) and if you were looking for something a tish bigger (and willing to deal with the added lines and such needed it would also be a pretty good setup.
Anything bigger than an evo3 16g or the hta68 is going to be a lot more money for not as much gain. If he's new to the dsm world, he'll likely need to be reminded that supporting mods are often what make or break a setup: cams, proper fuel support, intercoolers, eliminate piping restrictions, etc.