The R6 is an elegant warrior, with sharper lines which will catch the attention of even the less interested onlookers. We have developed an Akrapovic SLIP-ON aftermarket component which will elegantly replace the stock muffler. Your R6 will get a face-lift, a throatier sound and of course a performance upgrade as well. The elegance of the Akrapovic SLIP-ON package will please those riders who are relatively satisfied with the stock characteristics of the R6, except for the bulky stock muffler. You also get increased performance and a high-tech approach to both production and materials selection. For 2005, the R6 delivers more power than the 2004 model.      Performance  Measurements of the Akrapovic SLIP-ON system on the YAMAHA YZF R6 (without muffler insert):  Power & Torque: the Akrapovic SLIP-ON system is not designed to pull the absolute maximum out of the engine; we have other systems in our range which will do that. However, even with this first-level component you will receive a boost in power. It starts around 3000 rpm and stays higher than the stock curve all the way to the top of the rpm range. With the Akrapovic SLIP-ON system you get an extra 1.8 HP at 13200 rpm, which puts 109.7 HP into the rear wheel of your Yamaha.  We managed to increase the torque from 2800 to 4000 rpm, after which the Akrapovic torque curve is identical to the stock curve until 4800 rpm. Above that, the Akrapovic curve exceeds the stock figures all the way to the top of the range.