Flew a clean F4K on a test flight out of Yeovilton. Part of it was to check the movements of the ramps. So having followed the profile and at about 38,000ft or thereabouts in full burner, continued to accelerate to see how it would go. Managed 2.2M. The next problem was slowing down as there had been a couple of flameouts coming out of burner. Therefore, somewhere just west of Chivenor, laid in about a 3 G turn to starboard, and gently eased both engines back to min burner. Follow by easing them individually back in to military power. This turn appeared to take up most of the Bristol Channel.