Artificially constrained schedules and inappropriate budgets will doom a project regardless of the quality of the people or the availability of tools, languages, and process.
If you try to compress either schedule or budget, the engineers working on the project will not work efficiently, there will be no wiggle room when the inevitable slippage occurs, morale will suffer, and the project will probably cost more than what would otherwise be considered reasonable anyway.
In short, tightening a schedule or budget to land a contract or to get stakeholder sign-off will only ensure your failure to deliver. The goal isn't to get project approval. The goal is to get approval for a project that can actually succeed.
Reference:
DeMarco, T., "Why Does Software Cost So Much?" IEEE Software, March 1993.
