I ordered my first collection of SP gear yesterday and looking forward to using them. I've managed to get my hands on a complete Porsche 997 gauge set which will make for a really cool dash on my simrig, and will end up connecting the tacho and the speedo of that set to the two Rev Burners I ordered. However, the set also comes with a variety of other common gauges (e.g. fuel level and oil pressure) and lights (like turn signals and a handbrake indicator). I'm hoping to get at least some of these to work if only because it looks cool - besides fuel level there's hardly any others that would even make sense to monitor during most sim races.
Although I don't really know a lot about the internal electronics of a car dash, I guess the speedo and tacho are the only gauges that work with pulses. This would mean it's quite complicated to use a Rev Burner for e.g. the fuel gauge. Switching lights on/off is a different story entirely.
I have not looked at SimDash in detail but I get the impression it's not intended for use with home-made externals. I was hoping to DIY some PCBs together and hook it up to SimDash, but from the looks of it that will be very difficult without access to the source code. If it is possible, I'd like to know how - if it isn't, do you plan on making this possible in the future?
Another solution would of course be to release new products; one that supports other types of gauges (or new firmware that somehow enables the Rev Burner to do so) and one that enables switching (or even blinking) lights.
Please don't think that I'm criticising you for not supporting some of these components I mentioned: I'm psyched to be able to use a proper tacho and speedo alone and understand that these are by far the most important ones to go for. However, as a sim fanatic I'm always hoping to add more stuff to my rig and making it look as real as possible, and hence hope that this will be possible one way or another in the future.

Jelco