Bike – 2005 R1200GS
It is a well known fact that removing the catalytic converter from the GS exhaust system will open up a whole new dimension to the way that the bike performs. Better mid range performance and sharper throttle response being the two key benefits.
A BMW Akrapovic can was already fitted to mine in conjunction with the OE headers. There was certainly an increase in throttle response together with a much throaty exhaust note utilising this configuration.
To uncork just that little power rider friendly power I decided to fit the Remus headers as a replacement for the BMW OE headers.
There are three subtle differences between the OE headers and the Remus ones: -
1) Remus headers do not have the catalytic converter fitted.
2) Remus omits the connecting balancer pipe between the two cylinders.
3) Overall diameter of the Remus headers is approximately 4mm larger than OE.
It is a very straightforward installation to do and one that should only take about 1½ hours from start to finish. It is advisable to fit new header gaskets in the replacement process.
That said, if you have the Touratech bash plate extension and or the Touratech main stand plate fitted, these should be removed in order to make it a header replacement process a whole lot easier!
The difference in performance is quite remarkable to be honest, the throttle response is now so much quicker and instant, also the low & mid range hook up is totally transformed.
The whole power curve seems to be evened out to be a more rider friendly advantage. There is still however a very defined power surge when you get towards the upper rev limits.
Personally I quite like this, as its like having a secondary kick when you most need it.
The engine runs and performs very smooth indeed with no apparent fuelling issues in any apart of the entire rev range. The bike has now covered just under a 1000 miles since the Remus headers were fitted and I have nothing but praise for the set-up and would have no hesitation at all in recommending it.
Dependant on your point of view, but a consequence of removing the catalytic converter is the exhaust will now cackle & pop when the throttle is closed and the engine is on over run. Once again personally I quite like this, but others might find it annoying?
Despite having no issues regarding the performance and the running, I was still a little concerned about the possibility of the engine running lean?
I contacted my local BMW dealer who suggested that the bikes ECU would figure out any fuelling concerns. The Remus headers were a recognised retrofit and as such would not create any adverse fuelling conditions. The main advantage is the removal of the catalytic converter, this allowing sub standard quality fuel to be used for those travelling in remote parts of the world.
The BMW Arkopovic can is also a recognised and approved BMW aftermarket part, and will also not have any adverse effects on the fuelling.
As was pointed out to me, a main BMW dealer would simply not supply these parts if there were ANY concerns at all regarding the performance of the engine or any possible warranty claims.
But being a compulsive tinkerer I just had to explore the next tuning stage, this is in the form of the Wunderlich Power Controller.
I am also very lucky enough to have been given a Power Controller and also K&N air filter in order to conduct my own tests.
The fitment of the Power Controller (PC) could not be any easier, simply unplug the two OE fuel injector plugs and also the two oxygen sensor plugs located in the headers and then just plug in the corresponding leads in from the PC. Finally connect a black wire from the PC to the earth post on the battery earth and that’s it done!
No need to remove the fuel tank, just the removal two small plastic side covers and the both the seats, total installation time around about 1/2hr.
Now follow the simple instructions regarding the reprogramming the ECU. Ignition on, but engine note started, open throttle to fully open to closed three times, switch ignition off.
The instructions included in the kit show two base setting for the PC, one for a standard bike and one for a modified bike, i.e. Remus headers, high air flow air filter, open exhaust can.
The bike was started and the PC set to the latter base setting, the exhaust note was certainly a deeper sound, due to the increase in the supply of fuel.
On a road test over 80 miles the throttle response appeared to be more responsive and the engine certainly spun up a whole lot quicker. So much so, that pulling away aggressively in first & second gear will see you hitting the rev limiter very quickly indeed!
Changes that have been noted are the tick over speed has increased and so to has the fuel consumption. Plus any popping or cackling from the exhaust on throttle over run has now ceased.
I “think” that the throttle response has improved low to mid range but it is very difficult to measure by the seat of your pants. That said when you are travelling at high speed in sixth, the throttle response could only be described as a bit woolly, certainly not as clean as it was pre-PC fitment.
But I do know that there is no increase on the overall top speed though. The power surge mentioned before is still noticeable towards the upper end though, I did expect to see this smoothed out?
At a constant low’ish road speed, such as 30mph in a built up area, I was aware of what can only be described as a minor amount fuel surging. This condition was also noticeable pre-PC fitment?
That said, with some minor tweaking on the PC mode + & - buttons I expect that this could be ironed out?
At the end of the day every bike is different and as such there has to be a certain amount of fine-tuning required in order to gain optimum results. But personally I would suggest that the bike is set up on a rolling road to determine exactly what the fuel mapping is doing across the whole rev spectrum. Gauging performance by the seat of your pants in an uncontrolled environment is not really acceptable to me as I am a “figures on a chart” person.
I also conducted the road tests with a standard air filter and also a K&N filter. To be perfectly honest I could not notice or feel any particular benefits in performance what so ever? I would love to see the dyno chart differences though?
Pre-PC fitment the bike ran 100% perfect with no running issues at all.
Post PC fitment, overall pleased with the results but IMHO a session on a rolling road could possibly see more advantages….maybe?
But at what cost, £300 Remus Headers, £500 BMW Akrapovic can, £250 for the PC, £40 for the K&N air filter, and then £40 per session on a rolling road? It’s an awful amount of money to spend; especially taking into account that it’s a heavy old GS and not a lightweight sports bike?
Perhaps the old saying is the most suitable: - “If it’s not broken, then don’t fix it”
I would however certainly recommend the Remus headers and the BMW Akrapovic can, but I am not entirely convinced about the rest, would like to see hard data to support the claims.
It is a well known fact that removing the catalytic converter from the GS exhaust system will open up a whole new dimension to the way that the bike performs. Better mid range performance and sharper throttle response being the two key benefits.
A BMW Akrapovic can was already fitted to mine in conjunction with the OE headers. There was certainly an increase in throttle response together with a much throaty exhaust note utilising this configuration.
To uncork just that little power rider friendly power I decided to fit the Remus headers as a replacement for the BMW OE headers.
There are three subtle differences between the OE headers and the Remus ones: -
1) Remus headers do not have the catalytic converter fitted.
2) Remus omits the connecting balancer pipe between the two cylinders.
3) Overall diameter of the Remus headers is approximately 4mm larger than OE.
It is a very straightforward installation to do and one that should only take about 1½ hours from start to finish. It is advisable to fit new header gaskets in the replacement process.
That said, if you have the Touratech bash plate extension and or the Touratech main stand plate fitted, these should be removed in order to make it a header replacement process a whole lot easier!
The difference in performance is quite remarkable to be honest, the throttle response is now so much quicker and instant, also the low & mid range hook up is totally transformed.
The whole power curve seems to be evened out to be a more rider friendly advantage. There is still however a very defined power surge when you get towards the upper rev limits.
Personally I quite like this, as its like having a secondary kick when you most need it.
The engine runs and performs very smooth indeed with no apparent fuelling issues in any apart of the entire rev range. The bike has now covered just under a 1000 miles since the Remus headers were fitted and I have nothing but praise for the set-up and would have no hesitation at all in recommending it.
Dependant on your point of view, but a consequence of removing the catalytic converter is the exhaust will now cackle & pop when the throttle is closed and the engine is on over run. Once again personally I quite like this, but others might find it annoying?
Despite having no issues regarding the performance and the running, I was still a little concerned about the possibility of the engine running lean?
I contacted my local BMW dealer who suggested that the bikes ECU would figure out any fuelling concerns. The Remus headers were a recognised retrofit and as such would not create any adverse fuelling conditions. The main advantage is the removal of the catalytic converter, this allowing sub standard quality fuel to be used for those travelling in remote parts of the world.
The BMW Arkopovic can is also a recognised and approved BMW aftermarket part, and will also not have any adverse effects on the fuelling.
As was pointed out to me, a main BMW dealer would simply not supply these parts if there were ANY concerns at all regarding the performance of the engine or any possible warranty claims.
But being a compulsive tinkerer I just had to explore the next tuning stage, this is in the form of the Wunderlich Power Controller.
I am also very lucky enough to have been given a Power Controller and also K&N air filter in order to conduct my own tests.
The fitment of the Power Controller (PC) could not be any easier, simply unplug the two OE fuel injector plugs and also the two oxygen sensor plugs located in the headers and then just plug in the corresponding leads in from the PC. Finally connect a black wire from the PC to the earth post on the battery earth and that’s it done!
No need to remove the fuel tank, just the removal two small plastic side covers and the both the seats, total installation time around about 1/2hr.
Now follow the simple instructions regarding the reprogramming the ECU. Ignition on, but engine note started, open throttle to fully open to closed three times, switch ignition off.
The instructions included in the kit show two base setting for the PC, one for a standard bike and one for a modified bike, i.e. Remus headers, high air flow air filter, open exhaust can.
The bike was started and the PC set to the latter base setting, the exhaust note was certainly a deeper sound, due to the increase in the supply of fuel.
On a road test over 80 miles the throttle response appeared to be more responsive and the engine certainly spun up a whole lot quicker. So much so, that pulling away aggressively in first & second gear will see you hitting the rev limiter very quickly indeed!
Changes that have been noted are the tick over speed has increased and so to has the fuel consumption. Plus any popping or cackling from the exhaust on throttle over run has now ceased.
I “think” that the throttle response has improved low to mid range but it is very difficult to measure by the seat of your pants. That said when you are travelling at high speed in sixth, the throttle response could only be described as a bit woolly, certainly not as clean as it was pre-PC fitment.
But I do know that there is no increase on the overall top speed though. The power surge mentioned before is still noticeable towards the upper end though, I did expect to see this smoothed out?
At a constant low’ish road speed, such as 30mph in a built up area, I was aware of what can only be described as a minor amount fuel surging. This condition was also noticeable pre-PC fitment?
That said, with some minor tweaking on the PC mode + & - buttons I expect that this could be ironed out?
At the end of the day every bike is different and as such there has to be a certain amount of fine-tuning required in order to gain optimum results. But personally I would suggest that the bike is set up on a rolling road to determine exactly what the fuel mapping is doing across the whole rev spectrum. Gauging performance by the seat of your pants in an uncontrolled environment is not really acceptable to me as I am a “figures on a chart” person.
I also conducted the road tests with a standard air filter and also a K&N filter. To be perfectly honest I could not notice or feel any particular benefits in performance what so ever? I would love to see the dyno chart differences though?
Pre-PC fitment the bike ran 100% perfect with no running issues at all.
Post PC fitment, overall pleased with the results but IMHO a session on a rolling road could possibly see more advantages….maybe?
But at what cost, £300 Remus Headers, £500 BMW Akrapovic can, £250 for the PC, £40 for the K&N air filter, and then £40 per session on a rolling road? It’s an awful amount of money to spend; especially taking into account that it’s a heavy old GS and not a lightweight sports bike?
Perhaps the old saying is the most suitable: - “If it’s not broken, then don’t fix it”
I would however certainly recommend the Remus headers and the BMW Akrapovic can, but I am not entirely convinced about the rest, would like to see hard data to support the claims.
)....
Nice write up Alan,I am considering the Power Controller too,I have Remus headers and can (baffle IN as I'm not completely anti-social
Not withstanding the £600 fine and the 6 points in one hit. 
