5 months too late, but I have an OS 160, vp30 pump, APC 18 x 6, tank on CG, bisson pitts style muffler. I can fly "3-D" for about 25 minutes on that tank!! and it pulls better then the YS 140, even at 3000 msl!!! lets see... Hmmmmm..... $250.00 verses $600.00.... same power..... better fuel economy... fewer parts, easier starts... Hmmmmm... YES OS!!!!