The Horizon header and pipe are whisper quiet, quieter than the stock muffler. It's a muffled tuned pipe. Steel header (which is what you want on a gasser) and lightweight aluminum pipe. If you can daal with the length of the setup on your plane, this is the one to get. I'd recommend it for any of the small weedie conversions and just do whatever you have to do to make the header fit your motor. No tuning required, it's all plug and play. But if you want to try something else, Macs Products makes some aluminum headers for the G-23 and one for the Homelite 25.