I like pumps!! I like mounting my fuel tank right over the CG and a pumper allows me to do this. With a pumper the fuel is regulated so there aren't any lean or rich moments due to the the attitude of the plane. The only problem I have had is getting one small little part for my regulator from OS, a diaphram. There is one in a YS too and every couple of years it needs to be replaced but they are cheap and I usually have them on hand. The YS is the better engine, it runs very well on 15%, I have even run them on 5%. There is no difference between the engines when you tune one, a high and low end needle. That big brass screw that freaks everyone out is just the pressure regulator and for the most part you never have to touch it. I have found my YS engines less of a problem then the Saitos but none of them are ever very cranky. I am wondering about the 9 pounds though. The YS has the beans for it but I'm not sure how well it would do with the 3-D part. 9 pounds is a bit heavy for it. Joe, I will have to weigh my Mid West Hots for you and I could let you know. It's a heavy little plane and my 1.10 YS can pull it straight up out of a hover, I can't remember but I think it's about 7 pounds, maybe more?? I'll let you know. I did use a YS 1.40 sport on a Goldburg Extra, that's a heavy 68 incher, OH MY!!!!! Wish it was my engine!!!