A engine made by me.Took 2 days but it was worth it in my opinion.This engine is the RAPID-2E with the exhaust pipe which works !!!!!!. no XML editing.It can be used as a second stage engine or upper stages for more thrust.
if u want to attach it in your craft,
there is a fuel adapter under the command chip.
drag it add to sub-assemblies. and attach to ur craft.
PLEASE UPVOTE AND COMMENT IF ANY PROBLEMS