The Austrian-built Rotax V-twin is plenty strong in stock trim, but more power is always better, right? To that end, I was one of the first to lay hands on the new FMF carbon-fiber/titanium Apex slip-on ($549.99; www. fmfracing.com). It's a straight-through design with a removable and reversible insert that fits between the muffler and mid-pipe. There are three different ways you can run it, each showing increases in both horsepower and torque on the dyno. Pretty solid bang for the buck, especially when you consider the 15.4 pounds it saves. Not surprisingly, the highest peak horsepower (132.9 bhp, exactly 5 more than stock) is with the diffuser removed altogether. For commuting, I use the most restrictive setting. It still has plenty of bark, but isn't too offensive when creeping through residential areas.