Hey, I am new to this site and it looks great. Anyway to the point. I have recently purchased an e30 318is. It needs a new cat and back box. Am looking for something that is quiet but a deeper tone. Not much louder than stock. Whats the best makes and what should i stay from. I also have a strange starting problem. Most times it starts fine, but sometimes it will stay turning the engine over and won't start. Turn off the key and turn it back on again and it starts fine. Then runs a bit rough after start up but is fine after a little rev. Any suggestions?