An os off of tower hobbies. They always have extra discounts you can use on there products. I bought a OS 1.20 w/o a pump for my GP GeeBee and they gave me 40 dollars off and I am not bsing. I love my os better than my saito 100, it runs a whole lot smoother and the idle is smooth too. On my saito the idle is crap. I have been trying to get my needles set on the saito but it still knocks like crazy. Right now I can get the os to idel as low as 1800 without any knocking and the saito idles at around 3000 biiiig difference. I still love the saito though, I would buy another but right now I would get an os before a saito.