Having first tried a Supertrapp 2:1 system back in 1989, we now have over 20 years of experience working with this style of pipe. The current Supermeg version of the 2:1 has been with us since the early 2000s, and is, in our view, arguably the best all round performing exhaust system for a street ridden Harley. The sad fact is that most aftermarket Harley exhausts are there just to make a noise. Many of them will either give a reasonable torque build at low rpm (at the expense of mid and upper range) or a high peak horsepower number with an atrocious dip in the torque curve right where we ride most often.
Noise is also becoming more of an issue, particularly at MOT time, and if you value the friendship of your neighbours. Noise does not equal power! From a tuning point of view the Supertrapp Supermeg is easy to work with, as unlike many Harley exhausts, it works with us, not against us. Most Harley pipes use a cheaply made mechanical baffle which gives the rasping exhaust note that many of them exhibit.
The Supemeg, however, uses an absorption type baffle that removes this type of noise. Attached to the end of the baffle is the facility to add a number of diffuser discs with a closed end cap. The significance of these discs is the gaps between them, which is where the exhaust gasses escape. More discs equals more gaps, and by altering the number of discs (and therefore gaps), we can control the way the power is produced, as well as the noise level. So we effectively have a tuneable exhaust. It is also the case that Harley engines like a 2:1 pipe. The best performing exhausts from other manufacturers ranges are also 2:1s.