The theorists and the practical results don't always line-up...,,
There's the documented story about Shelby bringing in Benny Howard (aeronautical engineer, test pilot, airplane racer, airborne bootlegger) to give an opinion on Pete Brock's Cobra Daytona prototype. Howard's expert opinion was that the Daytona would need 450hp to achieve 150mph (interesting, compared to what the roadster could already achieve).
Shelby had around 380hp available, and wanted 170mph from the Daytona.
Brock said "trust me", and we know the rest of the story
Cheers,
Glen