THE F.P.E 2.4 40CC IS 51OZ WITH IGN. AND MUFF. BUT THE OS BGX-1-3500 35CC IS 49.6 OZ WITHOUT MUFF. BOTH HAVE SAME H.P. SO THAT IS 1.4OZ DIFFERANT.THE FPE WEIGHT IS WITHOUT BATT. AND SWITCH BUT THE OS IS WITHOUT MUFF.HOW DIFFERANT CAN THEY BE COUPLE OF OZS.SORRY I JUST DONT UNDERSTAND??!!