Got the books out and here you go.
The only Allied use of nitrous oxide was one squadron of night fighter Mosqitos Mk XIII’s (50 aircraft in all) had the system fitted to their RR Merlins in order to improve speed and climb rate above 20,000 feet for short periods of time.
Janes “All The Worlds Aero Engine” has the following,
Nitrous Oxide Injection – This power boosting system was first referred to by the Germans by the code name “ha-ha”, nitrous oxide or “laughing gas” being injected into the supercharger. The nitrous oxide was retained under pressure in liquid form. The system was designated as GM 1.
Installation – In a twin engined aircraft (Ju 88 S) the liquid is carried in three cylindrical containers arranged pyramid fashion, located in the fuselage. Later aircraft had a single 75 gallon cylindrical container. Compressed air cylinders contained the air for forcing the liquid along the pipe lines to the engines. The complete installation weighed 400 pounds dry and the weight of the nitrous oxide was 900 pounds assuming full tanks. The tanks were heavily lagged with glass wool and enclosed in a shell of light alloy to prevent evaporation.
In the Ju 88 S-1 (BMW 801 G-2 engines) injection was arranged at two rates, “normal” 7.95 lb. per engine per minute and “emergency” 13.2 lb. per engine per minute. The endurance of the systems at the two rates was 27 mins. and 45 mins. respectively.
Performance – This power boosting system was used above the rated altitude of the engine. The nitrous oxide provided additional oxygen for the engine, and also acted as an anti detonant. Part of the increased power obtained was due to its charge cooling qualities.
The Ta 152 B aircraft with a DB 603E engine had a maximum speed of 417 mph at 27,000 feet. When the GM 1 system was used at an injection rate of 13.2 lb/min the maximum speed was increased to 348mph (that’s what the book says – think they may mean 448mph which coincides with other sources) at 32,800 feet. The increase in horsepower was 350 HP at 32,800 feet.
With the Jumo 213E engine installed in the Ta 152 B the maximum speed with out GM 1 was 439 mph at 35,000 feet and this was increased to 443 mph at 44,300 feet with the maximum rate of injection of 19.8 lb/min. This represents an increase of 418 HP.
Other systems the Germans used
Methanol water injection MW 50 49.5% by volume water, .5% anti corrosion, 50% methanol
MW 30 69.5% water, .5% anti corrosion, 30% methanol
Me 109 carried 25 gallons, also used on Ta 152 B , Fw 190 (DB 605, BMW 801 and Jumo 213A engines). Ta 152 H high altitude reconnaissance carried 18.6 gallons of GM 1 and 15.4 gallons of MW 50
Ethanol water - used in place of MW 50 49.5% water, .5% anti corrosion, 50% ethyl alcohol
Pure water injection (BMW 323R and Jumo 213A engines) the Jumo could develop 1,650 HP with pure water and 1,670 with MW 50 against a basic power of 1,610HP (high supercharger, +8 lbs. boost)
Petrol injection into the air intake – used on Fw 190 with BMW 801 D engine (1,730 hp at take off increased to 1,870 hp with petrol injection. The injection allowed the normal take off boost limit of +5.5 lbs to be increased to +8.8 lbs)