Final engine mods
I'm usually not one to carry out engine modifications because they nearly always result in increased noise or reduced reliability.
The previous owner had drilled 10x 10mm holes in the top airbox and removed the snorkle, which has the same effect as the 3x3 mod over on ThumperTalk. This increased induction roar (bad) but made the bike much smoother to ride without making it too lean. I found the noise too much going through France and Spain.
At the same time I had bought a FMF full exhaust, loud to say the least, but with the restricted header at the front removed and the holes in the airbox I was getting rediculously good mileage. As I recall stating, it cost £22 from Newcastle to Dover at 96p ~ Gallon. Back on the 1150GS it cost £28 to get to the top of Hertsfordshire, North London fringe!
But the noise was too much and the bike was put back to standard. I have yearned for the extra power and smoothness, not to mention the significant rise in MPG and that got the plastic working:
Added to the list:
- TwinAir air filter
- DEP stainless header
The DEP header is an exact copy of the original which means it can be used with the OE silencer. It doesn't have the restrictive washer in the middle pipe and so noise goes down and smoothness goes right up. I talking noticeably.
The Twinair filter (still a sponge

) is two stage and somehow, no idea how, the induction roar doesn't go through it. Thus I could open the holes in the airbox back up.
All this should make the bike run really lean, but it doesn't feel it (high reving with no go). It's no longer starved for air and it doesn't have the snatching at low speeds. The OE silencer still provides enough back pressure to keep the torque up right across the range and it shifts now - not far off the 1150GS!