quote german FW190 Wikipedia translated to english:
"The A-8 variant enabled the Fw 190 for the first time to use the MW-50 system for a short-term increase in engine performance, which had already been planned in earlier variants but had not yet been successfully implemented. [32] For this purpose, the aircraft was equipped with a tank of 115 liters capacity behind the pilot's seat to receive the methanol-water mixture. This tank could alternatively be used as an internal additional tank for gasoline and made it necessary to move the radio equipment directly behind the pilot's seat. At the same time, the pilot's oxygen cylinders were moved to the rear and placed around the new tank. Access was via a round access hatch on the underside of the fuselage, immediately behind the wings, where the A-8 variant can be easily identified
...
In addition to the performance-enhancing MW-50 system, the A-8 was equipped with increased emergency power as standard from July 1944. This made it possible to increase the boost pressure at ground level from 1.42 ata to 1.58 ata and at higher altitudes to 1.65 ata. Depending on the altitude, this measure led to an increase in the top speed of between 22 and 25 km/h, which, for example, increased the top speed of the Fw 190 A-8 from 548 km/h to 578 km/h near the ground and from 644 km/h to 652 km/h at an altitude of 6300 m. In contrast to the C-3 injection system, no additional fuel was required here. As with all systems for the engine's special and emergency power, its use was limited to ten minutes (although it could be used several times per use after the engine had cooled down)
...
but lets just stick with the canopy glass bug for now..