Its not gunna get that loud like a muscle car chugging kinda loud if thats what you want, ther ain't enough power.
Not enough stroke and cubes.
You need a certain amount of back pressure for the engine to work efficiently, running straight pipes can also give you valve problems like valve warpage.
Not enough stroke and cubes.
I'm no expert, but I've never heard of a muffler improving an engine's efficiency over straight pipes.