I just got the GP Ultimate 160 version and total weight after build and radio gear in was 15 LBS now GP recomends a fuji 43 cc gas as a max , But I went ahead and put a DA50 on her instead , I also want to coution you if your GP is a arf be very carefull about what size engine you use , When I got mine last month its says only 20 hrs to complete, well needless to say it took me about a month , Why? becouse I stripped it down and recovered it to a scale sheme (tired of all the Ultimates looking the same) Lol Lol Anyway after stripping it down I found 22 spots on the fuse and the wings that didnt even get glued , after fixing them and going over the rest of the plane with a fine tooth comb this is what I ended up with and man can she fly , Ive got the CG right where GP recomends and all the throws on minimin and she 3 D's like no one ever saw. Good luck in your project , Grant it not everyone will go through there ARF like I did But good luck just the same.