Which Akrapovic?

[Dezi58]

I didn't do a before and after dyno test because that would have been both expensive and inconvenient. My initial motivation was to get rid of the standard headers as the valve had seized. I decided on the Akra headers in stainless - more robust than titanium - and then went the whole hog with a servo buddy and Hilltop remap. It doesn't really need the servo emulator but they're not expensive and it avoids having an exposed connector where it is bound to corrode.

The bike doesn't just feel better, it is materially faster. It pulls from below 2,000rpm and the acceleration in 6th at 50/60mph is stronger, less need to change down. The surprise is that it is much more economical unless you are caning it. I got high 40s riding from London to Leicester and mid-50s going home. It delivered 65mpg on a recent road trip with a mix of motorway and A-roads. I'm going on a trip soon with a mate with a new R1300GS, it will be interesting to swap bikes and do a direct comparison. I rode a 1300 in Romania and it felt no faster than my 1200 and was less happy trickling through town at 2,000rpm.

I have had lots of GS's and I have had other bikes remapped too. This remap was the best I have ever experienced.

Regarding the advice from your race engine company, that sounds very....odd. Removing the cat and valve, and adding larger diameter headers with better gasflow will do much more than changing the silencer. And removing the O2 sensors means that the ECU has no way of knowing how the engine is running.

Thanks for the reply, always good to hear from someone who’s got first hand information having spent money. Wrt the engine tuners comments, it’s quite difficult to keep conversations in context when writing posts however what they said was in reply to my proposal to buying a certain brand of headers, was not to bother as they had experienced some very bad results with particular brands. So advising me to stay with the stock headers was in the context of me using cheap headers albeit on a GS Wrt the O2 sensors, they said they would unplug them at some point when remapping the engine, (i have no idea why) however this company has been around for years and does hundreds of race bike engine tuning (with a huge amount of repeat business, (can’t fit me in til January) and engine rebuilds so they definitely know their onions so your view on the issue of bigger headers = better gas flow etc etc and O2 sensors / ecu’s is a generally held opinion (mine as well) doesn’t mean to say it’s better then standard headers / new silencer or even leaving the bike completely standard and just remapping the ECU, performance tuning is a black art and the obvious isn’t always best, cheers PS they specialise in race bikes / fast road bikes not adventure bikes

 

[ProdigalGS]

Two tips if you decide to change the headers. 1) Unplug the lambda sensor wires before you unscrew them. The wires are solid conductor, not stranded, and they will snap if you twist them too much. That means buying a new sensor, which will definitely spoil your day. 2) The manifold stud nuts are an unusual 12-point design and you need a 12-point socket, not the usual 6-point hex design. I realised this partway through the job, luckily B&Q sell an appropriate socket. Also, there was a thread here by some poor guy whose stud nuts had corroded solid. New OE nuts are copper (and cheap), so they will be easy to remove in the future.