It's more your gearing that will limit you as a bit more hp just gets you there quicker but it would take a significant gain to actually gain more top speed. My Eclipse topped out at it's drag limited speed with it's stock 195hp so it wasn't faster with almost 400hp but it attained it's top speed in nearly the 3rd of it's stock time.
'12 Focus Red Candy SE Sport 5 spd
'99 Toyota 4Runner Sport
'11 Subaru WRX STI Hatch