my gx390 wont fit on my dingo with the stock muffler so i took it off and now its the header and nothing else. what should i do, put a pipe on there or leave it as it, i dont care about sound just dont wanna mess up engine
Engine will not be hurt.
Block will not crack and valves will not burn or become otherwise damaged.
I've done it for many seasons (summer) without as much as a hiccup.
Its not bad its just people usually want to direct the exhaust gases elsewhere or want to make it look cool. Its only a small engine, they can take a bit of abuse and things can be done a tad on the dodgy side.
Buy or make a header that is around 12" long overall. If you are just referring to that stock manifold/J bend they have on them you may be ok but i wouldn't run that. You are sacrificing power and eventually life of the motor with that.