Bf-109F4Z: 670 Km/h at 6.400m and 2.890 Kg? (Rechlin tested)
Bf-109G1: 700 Km/h at 7.650m and 3.060 Kg (Rechlin tested)
These aren`t GM-1 figures, actually both are for 110%/WEP figures without GM-1; the F-4 is from Rechlin`s flight test, but probably not corrected for compressibility, but this can`t be confirmed.
The 700kph G-1 figure was calculated from the abovementioned F-4`s, but the conditions are not known. I`d say it`s reasonable for Notleistung/110%/WEP w/o comp. corr.
G-1 and G-3 should be identical, as their only difference was radio set fitted (HF vs VHF).
A datasheet showing the effect on the G-6/U2 is shown below, unfortunately, it`s of very poor resulution and it`s hard to figure out the exact specs.
G-6/U2
Apprx.
665 km/h at 8000meter at 100%
680 km/h at 10500 meter at 110%
Appearantly, there were a number of G-5/AS/U2 built. These must have been extremely potent high altitude aircraft..
The other is a Rechlin curve about the F-4 without, and the F-4/Z with GM - 1 injecion.
The third is graphically plotting the climb performance of GM-1ish and GM-1less variants.
Hermann Graf managed to set the new World Record in high altitude flight-14,300 meters (46,885 feet). Aircraft was Bf 109G-5/U2 iirc.
In a Me 109G-1/R2 with GM-1 (N2O injection), R. Klein had achieved 680 km/h at 12000 m and a ceiling of 13800 m.
Also (thanks to GG Hopp and HoHun)
Kurfrst - Kurz-Betriebsanleitung fr Flugzeugfhrer und Bodenpersonal fr GM 1-Anlagen in Bf 109 G.
To put it into context, the Bf 109K managed at full power 630 km/h at 12000 meters. And these GM-1 carrier planes were available in 41/42 already. The G-1/3/5 series also had pressurized cocpits, so these planes were/are the unrecognized high altitude queens.