Hello Tom, From: "Tom Brown" <tbrown@xxxxxxxxxxx> [...]
FYI: The non-twin-spark 1150s, at least quite a few of them, were probably the worst surgers ever. If you find you can't tame it or don't like the side effects of your fix, people have been very happy with retrotwin-sparking from San Jose BMW and probably others (Bob's?). You send the heads in, they drill them for you and supply you with a kit with all the BMWwiring and goodies you need to add the second spark...
[...]When I did my research into the after-market dual-plugging a few years back, the extra electrics that San Jose BMW shipped were not factory BMW parts. They were third-party. I have no data to support this, but I have heard that the issue with these third-party parts is getting them replaced when they fail (read "non-BMW, so not available from your BMW shop").
Of all the folks I contacted who got the dual-plug upgrade, all were very, very impressed with the difference.
-Steve Makohin '01 R1100S/ABSOakville, Ontario, Canada