When you say bolt-on do you mean a metal strap that wraps around the engine and bolts to the muffler? The Rossi 45 RE has no bolt holes or taps for bolts. It is a circular outlet with a o-ring in a groove. I E-mailed MAC's and PS last year but never got a response. I fly my Morris Fun Design/Rossi RE on week days when a few of the more noise tolerant retirees are the only people at the field plus the field is way less crowded and you can do the goofy stuff right over the middle of the run way. Hogging up the "zone" is really what gets flyers dander up on the weekends and not the noise.