All those spacers/pullies/'tunes'/higher octane/air intakes etc will net you no more than 3-4 hp total when you put them all together on an otherwise stock 94-98 3.8L V6 Mustang - and for how much $$? $400-$500? More?? Too much for the power gained, that's for sure. He'd get more power just doing a basic tune up on a worn out motor.
Trust me, I've spent over a decade looking at every way possible to squeeze power out of the pushrod V6 no matter what the cost.
1998 Roush: M112'd Aluminum block 4.6L 2V 6 speed track car
1999 SVT: Mostly stockish
1970 Mach 1: Resto-modded monster
2000 Roush #5004 - World's FIRST M112'd V6 Mustang. Sold, but not forgotten.