My 07 people S 250 was starting to look a bit tired, so we tore it down over the winter, replaced a bunch of plastic, new paint, new belt, replaced the rollers with Dr. Pulley 19g sliders and an Emgo reverse cone shorty muffler. The muffler was for an 1 5/8" and came with reducers, but not enough, so I found a bronze bushing with an 1.125: ID. 1.5" OD that worked perfectly as an adapter.
I considered buying an NOS MRP 300cc kit, but they're pricey and completely unsupported with MRP closing.