This details my attempt to install a fuel injected 4.3L v6 and 5 speed from a $500 chevy astrovan and a 1996 ford thunderbird differential into my '94 miata. My projected cost of the car complete with emission compliant exhaust, a/c, powersteering, etc is $2500 with a very mild 4.3L v6 with around 220hp and 270tq. 300hp with vortec heads($300), over 500hp with a paxton and around 9psi($2200).

 Miata's have no transmission support crossmember, unrebuildable driveshafts, independent rearends, and are very tight vertically in the engine compartment, especially toward the front. The firewall is vertical where most cars are at 45 degrees, making exhaust routing difficult.and headers must sweep forward from the rearmost exhaust port since the head will be less than an inch from the firewall, even with a v6.