The Yak shouldn't catch a G-10 at any altitude. No unperked plane should catch a G-10 between 5k and 30k. On the deck the G-10 is as fast as a P-51D. At 5k it does 400mph, at 22k it does 450mph. The only planes faster below 5k is the Typhoon, La-7 and Fw190D-9. At 30k the 109G-10, P-51D and P-47D-30 are dead even in speed.