Kyosho GT clutch and engine question

For clutch, why don't you use the original ones.
For muffler, if yours are buggy ones then it should probably be ok

is the spring not installed properly for any reason? my v1r uses similar clutch but has no such problems. please note run-in means low rpm. if it breaks after run in, then all similar clutch will break when engine runs.

Parts of rtr may not be properly fixed by chance