and just for the sake of saying it, if you ARE planning on making hidden parts illegal, know that you couldn't pick a worse platform than the miata to do so with. the car is so well known by so many that you'll be found out if cheating. it also means the speed secrets are largely already known - so follow the step by step and have a fast, legal IT car.

and you don't need to do it anyway. the oft-bandied about 125whp from a 1.6L SM motor tells me there's plenty of engineering safety factor in the bottom end of a miata to accomodate IT or SM builds.