In this article I only describe my own approaches. I do not give any warranty that my data is correct.
Working on your motorcycle is at your own risk!
In case of doubt please contact a qualified workshop.
I wanted to change the sound of my 690 Duke. After watching lots of videos and reading a lot of threads in forums, I chose the full exhaust system GPR Furore. This will replace the center and rear muffler. The original exhaust manifold and the position of the O2 sensor remain as is.
This exhaust system comes with a Vehicle Type Approval, if the CAT and both dB-Eater are installed. In my case the CAT and the dB-Eater at the end of the rear muffler were already installed. The second dB-Eater has the shape of a cone and has to be put into the entry of the rear muffler. The EC-approval/testnumber is located on the rear muffler and points to the bike when the muffler is installed.
- rear muffler
- center muffler
- connecting pipe
- bolts and nuts
- tension springs with rubber sleeve
- spring hook
- holder of the rear muffler
- a clamp
- extract of the type approval
- 2x dB-Eater and CAT
- GPR logo
I was pleased that the GPR logo comes not preinstalled on the rear muffler. I like the clean look without it.
Installation of the GPR Furore
First the stock exhaust system has to be dismantled. For that both of the clamps from manifold to center muffler and from center muffler to rear muffler have to be removed. After loosening the holder of the rear muffler it can be dismounted.
To dismount the center muffler you have to remove three bolts. One of them is blocked by the side stand. So you have to detach it to get access.
Now the GPR Furore exhaust system can be installed. It's important that the screws are not completely fastened until the whole system is installed. This could lead to unwanted tensions in the exhaust system. After everything is installed all screws are fastened with the recommended torque by KTM for the exhaust parts.
The first step is to prepare the holding ring of the rear muffler. The protecting rubber band has to be cut to the correct length and the metal ring needs to be formed to fit around the muffler nicely. Next the GPR center muffler is put in place. It's connected to the manifold where you can reuse the original KTM clamp. The GPR center muffler is screwed to the back right fixation point.
After the center muffler is installed the rear muffler is mounted. Keep in mind to install both dB-Eaters at this point to have the Vehicle Type Approval for the street. The connection pipe is tucked with its wide end onto the center muffler and secured by the delivered clamp. The other end goes into the rear muffler.
The original holding point of the stock exhaust is used to fixate the rear muffler. After that the tension springs between connection pipe and rear muffler are mounted. Finally fasten all screws with the recommended torque by KTM for the exhaust parts. The GPR Furore full exhaust system is now installed.
After my first 300km with the Furore I describe my impressions of this full exhaust system: The Furore tones the Duke's sound deeper and louder. But the Sound can easily be influenced by the rev range you are in. With the GPR Furore you can still drive through villages without having all eyes on you. However depending on the twist of your wrist you can get a really dominant and loud single cylinder sound. I'm very pleased with that.
As a supplement I give some information about using the GPR Furore together with side bags. You can still use bags after changing to the Furore system. In fact the GPR rear muffler sits lower on the bike than the stock one. On my tour through Sweden and Norway I had no problems at all.
Change of power and torque
In some forums I read that riders experienced dips in power or torque after changing to the GPR Furore system. I did not experience dips in power and torque. I use it on a 2015 690 KTM Duke (unrestricted power). In everyday usage I don't even feel like I am having a less powerful bike. I do expect that changing to GPR Furore has cost me a few HP since the mapping was not changed for this new exhaust system.
If you face problems like dips in power, you should contact GPR or consider a change of your machine's mapping.
What I did encounter was a change of torque. For me the torque curve has moved to lower rpms.
I noticed it especially in 3rd gear:
With the stock exhaust in 3rd gear at 3000rpm (about 50km/h or about 30mph) I couldn't ride the 690 Duke comfortably. That was the limit of that one cylinder motor were it started to cog.
With the GPR Furore exhaust the cog starts at 2600rpm in 3rd (about 45km/h or about 28mph). Therefore I can now ride more smoothly at 50km/h in 3rd through town. The total amount of torque did not change perceptibly.