The only 50cc plane that Hanger 9 makes -- AND you can fly in IMAC at levels above Basic-- is the 27% Cap 232.

They make larger planes for IMAC type flying, but they are not for 50cc engines. More like 80cc or 100cc

They make other planes that can be flown with 50cc engines, but they are not IMAC type planes. You could put a 50cc engine on the Cessna or the Sundowner, but you wouldn't want to fly either of them in an IMAC competition.

They make exactly ONE 50cc scale aerobatic plane that you'd want to use in IMAC competition. The 27% Cap 232.
http://www.horizonhobby.com/Products...ProdID=HAN2900

There are lots of other options out there. Wild Hare, BME, World Models, Airwild, Aeroworks, Chief Aircraft, the list is endless..............
If you're new to IMAC, pick one and fly it 4 days per week. Burn fuel. The plane, at this point, makes about 5% difference. Later on, if you get really good, go buy the one that you think is the absolute best. Thats subjective. What you think is the best will be the one that somebody else thinks is the biggest hunk of junk on the planet. Doesn't matter. They all fly. Just pick one and fly it.