make 225 sound better?

It's going to sound agricultural no matter what. IIRC the best one I heard on a combine had some sort of cylindrical baffled muffler. Maybe throw a Gibson on it and see how it sounds.

I love the factory style muffler and lawnmower sized exhaust pipe on my Valiant. Yea it doesn't fit perfectly and I've addressed some of that but it's so quiet.