The other morning my VX backfired twice (well a 'phut' noise) on 2 start attempts. It has started 99% of the time on the first push for the past 7 years. For the rest of the day it sounded grumbly and rough, only did 2 10 min trips.. I changed the spark ASAP, and it now starts first time. However, it feels like the exhaust is pretty lame. The engine is louder, and the noise seems to be coming from the engine, rather than the exhaust silencing it. I've checked for air leaks to no avail, and although there is exhaust fumes and the exhaust gets hot, the engine doesn't seem to mind even if I cover the exhaust end totally blocking it! Any ideas. Cheers!