IIRC in Alfred particular folders can be added, to be searched for apps. If this works separately from main search, it might help—you'll probably need to create a folder and dump symlinks to the apps in there.
Otherwise, apps can conceivably be added as keywords or something. Rather annoying since it won't pick up new apps automatically, but oh well. Myself, I prefer Alfred anyway since Spotlight doesn't do too much aside from launching apps, converting currencies and occasionally looking for files (the latter is not so useful when there are thousands of third-party code files on the machine, and Finder is not my IDE anyway).
P.S. Also btw, at least with Alfred, I don't need even a full word for most apps—just two to four letters: i.e. ‘fi’ is Firefox, and ‘do’ is Double Commander. Alfred quickly ranks results higher if they were invoked previously for the same input, so the desired app pops up in the results just after a few letters, and this behavior sticks around without perturbation from re-indexing. This also means that at first it pays to enter those couple letters and select the app with the arrow keys, since Alfred distinguishes between inputs of various length—i.e. might learn for ‘firefox’ but not for ‘fi’.
