I have tourney RD, brifters and 7 speed freewheel on my inexpensive hybrid and find it shifts very smoothly, quickly and quietly if adjusted just right. I really don't see how upgrading there would be worth it. If anything I'd replace the inexpensive barely adequate FD (at least on mine). It's shimano but has to be there lowest quality FD. I've been enjoying taking stuff apart and putting it back together too. I must have the best maintained big box bike in the country but I enjoy fiddling with it and making it as good as it can be. Agree on upgrading the brake pads but past that I don't plan on putting any money into my intro bike. My next bike will have better hardware, wheels, frame etc. etc. but for now I'm having a blast riding my cheap bike all over the place and that's what it's all about for me.