Hello, I hate the stock exhaust on the 305 on my 76 nova, it seems like for the most part everything is original however, I dont know what the size is. I am hoping if I put two new mufflers in, I can make the engine sound a bit better since this car seems to be fairly quite for a 5.0L. I plan on putting them in but I have no idea what the size is. If anyone knows, please let me know!!!