Someone recently posted the figures on replacing the standard exhaust with an aftermarket and all but one exhaust was basically a loss of power. I think only the Leo's saw a gain and it wasn't significant while the lasers saw a major drop in power.
Yes you are correct in that the bike can lose power/torque in the lower rpm range when you open the restriction in the exhaust. You can gain at mid and higher rpm. I think it was Yamamha that came up with a valve called the 'Exupvalve' for that purpose of having back pressure to help the engine develop more torque at lower rev's and then open up at higher revs. for more power
That's where it starts to get a little sticky. I don't know what significant low rpm loss there would be but would imagine it's not that noticeable.
Here's the sticky part. I noticed my cold warm-ups were sounding a little different and knew I was headed for a Power Commander or equivalent. So I got it and experimented with the maps. My cold starts were better but was never satisfied knowing my air to fuel ratio's were not correct and I would be spending $300+ to get it on the dyno.
For me my 2 Bro's exhaust cost $$'s plus a PClll plus a Dyno. Around $1300+ with my K&N filter. Yes it runs good. Yes I put Db killers on the exhaust. Yes I'm glad I was able to do it this way but geez it's expensive!!
I love how the 2 Bro's look and sound. The tips are magnesium. I have the cheaper aluminum cans and love them. Also there has been talk of how some of these companies won't guarantee carbon fiber cans because some suffer burnout under extreme heat stress.
Later,
Cliff
EDIT: Oh yeah the bike with me(Blue n White) on it.
