Mine flat spins well - I just do a rolling dive, full aileron to the left, then slam in full down elevator and full right rudder(still holding full left aileron) - then I add in throttle and slowly move the aileron stick to nearly full right. Every plane likes different things with the ailerons in a flat spin.

I can get it totally flat in an inverted spin - the nose is actually higher than the tail but it doesn't climb. Upright it will usually be slightly nose down in the spin. I'm using a Saito .91 with an APC 14x6, different engine/prop combinations might cause it to flat spin differently.