I have all sorts of combinations for my '98 YZ250, but it is quite a bit different than your '05 motor. My favorites are an FMF Gnarly with a Pro-Circuit 296 spark arrestor for woods riding, and an FMF Fatty with a Pro-Circuit 304 for MX. The silencers don't make much difference over stock, but the pipes really move the power quite a bit in the RPM range. Stock pipe is quieter (just a little) than the FMF's due to thicker construction.