FMUs run fine at lower boost levels. At higher boost levels, they create extremely high fuel pressures at the rail, as I've already said. It's this high pressure that eventually kills injectors. For the price of an AFC and a BTM, you could go with a Hondata S100 or S200 with boost. While a lot of people run 450s with just an AFC, it only allows you to tune the fuel map. You would need to be able to tune the ignition map in order to have a completely tuned setup. Too little fuel can kill a boosted setup, but too much timing can have the same effects. If you already have an AFC, then I would probably just get the 450s and not worry about a BTM if you're running moderate boost. If you want to run more boost, and want to be able to tune your ignition maps in addition to the fuel maps, then look into Hondata.