This paper shows how recent developments in obtaining guaranteed time-domain bounds for a given set of structured and/or unstructured frequency-domain bounds can be incorporated into the standard quantitative feedback theory (QFT) control system design methodology. Since QFT guarantees frequency-domain specifications, one can now determine signal levels as a function of time for signals both entering and leaving the plant before the design process begins. The result is that the system frequency-domain specifications can be tuned such that the plant input-output signals remain within specified amplitude limits, rate limits or time-dependent transient bounds. Although single-input single-output (SISO) systems are treated here, the same results can be used in multiple-input multiple-output or multiple-loop QFT feedback problems, both of which make use of SISO equivalents as described by Horowitz in 1992.