First off, when using a DA or 3W style ignition, you will have to build a mounting plate for the ignition pickup, as well as modify the crank hub to accept the interrupter magnet. then you will have to time the engine for about 28-30 degrees total advance at 5000 rpm or so. It's not the easiest of tasks for the novice modeler, but it can be done. Given that both the DA and 3W ignitions have proven to be very reliable now, a good solid installation would be a viable alternative, however. According to Dave Johnson at DA, the best way to time the engine is to have the engine at TDC and the interrupter magnet just PAST the pickup probe (shiny dot) on the inside of the pickup, and go from there. The diameter of the crank hub, and speed of the magnet, are kind of critical in this application, so be sure to have the OD of any adapter mated to the crank hub the same as the hub for the 3W's or DA's. I measured the hub on one of my engines, and it's OD is actually about the right diameter for a magnet to lay against without drilling, then simply afix a piece of aluminum tube to the outside of the hub, with a hole in it for the magnet, and position as desired. Keeping the adapter from moving is not hard, and JB weld or some small machine screws can take care of that.

Like I said, the diameter of the hub, and speed of the magnet, are what control timing on this style of ignition, so it's a good idea to get it right the first time and be careful with the "adaptatioon"

My headers are made from home-cut flanges, made from 3/4" hole washers and massaged with a Dremel tool to fit the BME exhaust flange size, then brazed to the short 25mm KS elbows available from DA. I've used both the 70 and 75cc canisters, and power is about equal with both, although the 75cc canister seems to make just a little bit more. I'm re-vamping my smaller fiberclassics 330 right now, which has about 5" headers, but they are going to be cut back in the interest of space considerations to move the canisters away from the sides of the plane. I'll wind up with just the elbow and about 1" to 1/2" of header straight pipe, and I expect the power to go up slightly as the BME seems to prefer this type of setup.

I actually tried some long headers, approaching the theoretical 38-39" overall exhaust tuned length that would tend to match the exhaust duration of the BME, but power REALLY fell off, by about 500 rpm over previously seen numbers. I slowly cut the headers back until I reached baseline rpm figures, then continued to shorten them and watched the rpm keep increasing, along with having to start richening the top end mixture as the engine flowed more air. My final results were over 7000 rpm on a Mejzlik 28-10 with just an elbow for a header, the 75cc canister inlets shortened to 3/4", and a very short coupler. Rpm for the Biela or Menz-s 28-10, or the Mejzlik 29-10 went to over 6400 rpm, and I'm sure that with shorter canisters and more testing time the rpm figures would increase even more. . THAT will be a project for this Winter.

One thing to remember about the recommendations coming out of Europe for the Pefa exhaust systems. . the systems are, first of all, a bit enthusiastic in their "ratings" of how well the canisters match engine size. I've found that going up a size is always a good idea. . But, when you go up in size of the canister, your total flow length and volume go up as well, necessitating a shorter header for optimum "tuning", which is what you get with a 70-75cc canister and very short 2-3" header on the BME110.

Hope this helps.