Ive got a Pica 1/5 scale Spitfire that comes in at 25lb. The guy I bought it from has a US 41 in it. I want more power and I also need plenty of weight up front. Does anyone know which Gas I can go to that will closley match the US 41. I was hoping to keep the muffler side of my cowl from being cut. The US 41 has the muffler in the back. I thought about ZDZ but im trying to keep the price a little lower than that HELP