Originally Posted by (sp?)
I wasn't looking for more horsepower (directly). I put the exhaust on it so I could hear the bike. I like to watch the road when I ride and hearing the exhaust allows me to shift the bike better. I didn't want an excessively loud bike and have been happy with StainTune exhausts on previous BMWs. It works as expected and I like it.
I didn't notice any substantial improvement in HP or Torque. The 5000 rpm dip is there with the stock system also. I liken it to a turbo - get it up above 5K and it takes off. As an extra benefit, the StainTune is much lighter than the stock system.
Like I said before we should do what we personally want to do with our bikes....put on or take off anything that our heart desires..we only have to please ourselves..
I love to run through mechanical issues to find out exactly what the cause and effect relationships are...in other words the what, why and when.
My questions and comments about a torque dip or flattening of torque curve were made to compare what happens with most after market exhaust systems on our Boxer motors...the after market exhausts trade off some torque at lower rpm [your charts show the torque decreases about 4,400 rpm and then starts up about a little past 4,800 rpm] for gains at higher rpms....
If you can find stock Tq/Hp curves you will not see these mid-range torque drops...but if you don't spend much time in that mid-range flat spot it doesn't matter that it is there...blip the throttle, you are past it on the way to higher rpms, the "5,000 rpm" launch you describe is where the torque slope on the stock motor steepens heading toward max torque...but since I ride almost entirely off road, that loss of torque in mid-range could become problematic for me...the even torque grunt off road is what keeps you in control...and linear is better than ups and downs..oh yes, I wear ear plugs and a full helmet, always have, so I shift by the feel of the motor and other mechanical sounds..never have used the exhaust as a cue...but then I don't like the pounding pulses of loud pipes, just my tastes.
Soooooo...glad you like the sound, the look and the feel...that exhaust system you have is one of the better after market systems and very popular.. enjoy!