not as loud as a regular macerator pump. What I didn't expect is the three different cycles to clear the bowl. Each time it fills a bit with water then the pump kicks in. In the half flush it just does it twice or maybe once. I'm not on the boat right now and I can't remember exactly how the half flush works. It sounds like your install went ok. You never know if you get a factory flaw until you turn something on. I thought I had a problem when I first pushed the flush button and nothing happened but then I remembered that I had left the orange and black wires disconnected at the motor. What a relief for me. Sorry you're having a worse time.