On the eec-iv stuff you have a few ways. One is to mess with the load scaling. The stock tune knows about how much air can enter based on engine displacement, but it gets iffy when he starts to see more than 100% VE. Second, spark tables can be rescaled to command significantly less timing above a certain load.
A MAP is the best way to do and I think the only add on MAP is the Anderson PMS.
Boost tuning is not for a 1st timer.
1989 LX 5.0 - 333 Mexican block, Eagle 4340 neutral3.25" crank, Probe SRS 9cc dome .040 psitons AFR 185 Comp heads, FTI HR cam 239/244 613/613, Edelbrock Victor 5.0, 90mm TB, BBK 1 3/4, C4 and 4500 Circle D converter, 4.10 gears
2012 GT/CS 5.0 - Yellow Blaze Tri-Coat metalic, A6, HID.