The best replacement for impact is effect.

The best alternatives to impact are rated as following:
★★★★★  effect
★★★★  affect
★★★★  intent
★★★  disparate treatment
★★★  drill
★★★  outcome
★★  impacts
★★  influence
★  impulse
★  armageddon
★  low impact aerobics
★  defender
★  high impact
★  model at hollister
★  impact
★  puncture warframe
★  treatment
  high impact aerobics
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  have an impact
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  fc toronto
  consequence
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  rotor sprinkler

Your alternative for impact is not listed? Suggest!
Speaking about impact, one probably shouldn't forget about influence.

Other search terms related to impact and their ratings are:
★★★★★ influence
You have in mind a companion for impact and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of impact in all years. Click on graph for more.
impact
effect
affect