Findon seamer Howell collected figures of 7-60 to ensure Steyning were bundled out for 142 in 39.3 overs.
Steyning always looked unlikely to defend that total and an unbeaten 74 from Mark Solway saw Findon home in fine style.
Findon skipper Bradley Bridson admitted it was a massive victory for his side.
He said: “It was a really pleasing performance, especially after a woeful display last time out.
“We were very good and fully deserved our victory.
“Curtis has been carrying a slight injury all season so decided to reduce his run- up.
“That looked to be a good decision as he ended up with seven wickets.
“Both Sam Dunkley and Mark backed him up really well and our bowling was great.
“I went early in reply but Harry (Metters) and Mark batted superbly and won us the game.
“We’ve had a tough few weeks but hopefully this victory could give us that lift we need heading into the upcoming games.”
After choosing to bat first, Steyning struggled as Howell ripped through their top order. The seamer dismissed all of the top five batsmen to leave David Kennett’s team in trouble.
Johnny Burfiend struck 35 from number three, while Oliver Collins made 20 but other than that few contributions were forthcoming.
None of Steyning’s final six batters reached double figures as they were eventually all out for 142.
Hywel Jones trapped Findon skipper Bridson in front for nine to leave the visitors 13-1.
However, a second-wicket stand of 125 between Metters (50) and Solway got Findon close.
Solway then stuck around, finishing unbeaten on 74, as Findon reached their target in 35.4 overs.
Jones and Gary Hunt both took a wicket each but that was not enough for Steyning.
Following their victory, Bridson’s side moved above Crowhurst Park and into sixth place.
Findon host fourth-placed Mayfield in the league on Saturday.
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