basic upgrades???

[LastofthevvV8's]

putting an Empire performance 3" engine back exhaust and a VCM OTR in my Wm Caprice L98 this weekend(time permitting)
then was thinking Chip Talk for tuning once they are installed.
Anyone used these before?
Any reason i shouldnt use them?
Hoping theres some increase in power.
Theyre cheap i know but its as far as the budget will stretch.

Any thoughts, advice would be greatly appeciated

Thanks in Advance