The 4-Isopropyl-phenethylamine is likely to be inactive, but you are free to experiment yourself. It has been mentioned in the following articles:
J.Prakt.Chem.; 29; 1965; 123-141.
Chem.Ber.; 63; 1930; 3029, 3043.
Bull.Soc.Chim.Fr.; 1950; 340, 344.
J.Amer.Chem.Soc.; 70; 1948; 3865.
J.Amer.Chem.Soc.; 80; 1958; 5270.
J.Org.Chem.; 23; 1958; 1979,1980.
J.Amer.Chem.Soc.; 76; 1954; 3656, 3658.
The amphetamine has only been mentioned in the following article, where it and several other monosubstituted amphetamine analogs were synthesized and tested for their anorectic effects. The activity was found to be so-so and considerably less active than amphetamine itself. The article is very interesting and worth reading.
Anorexigenic Agents: Aromatic Substituted 1-Phenyl-2-propylaminesGerald F. Holland, Carl J. Buck, Albert WeissmanJ. Med. Chem. 6(5), 519-524 (1963)
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https://www.thevespiary.org/rhodium/Rhodium/pdf/monosubstituted.amphetamines.pdf)