A power adder is a turbo, supercharger or nitrous. I assume you are instead talking about exhaust/intake mods?
One way to tune that in would be to install a wideband 02 kit to monitor A/F ratios. Then add a larger fuel pump and adjustable fuel pressure regulator, to turn up the fuel pressure a little to maintain a safe A/F ratio. Just one way to do it.
97 T-Bird LX 4.6 - 80k miles
94 Supra TT Auto - street/strip car
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95 T-Bird LX 4.6 - fully optioned, owned 15 years, 220k miles
96 Cougar XR-7 4.6- Brenda's car, owned 11 years, 187k miles
88 T-Bird 3.8 - first T-Bird, owned 5 years, 206k miles