I am willing to consider other engines and I am a big fan of straight bolt replacements. But the OS.18 is only marginally more powerful than the engine I am replacing.(On paper anyway) The Magnum NX has a NX3 engine claiming 3ci displacement. For all that it is 2 mph faster. I have considered the turbo engines but having suffer reliabilty issues already i am reluctant to choose a engine the revs to high 30000 rpms Almost any engine will cost about the same whether it is .18 or .46 you are only looking at a few dollars difference, which is usally to do with the popularity of the unit anyway. The tricky bit is mating it to the car.