the 1.8 miata came out in 1994...they did not have a factory knock sensor and handled boost VERY well

the NB miata did come with a knock sensor as i believe. a very popular setup is the 1994-97 1.8 block with a 99 head boosted...this is a very high flowing setup with a strong bottom end

if i money though, i'd swap my 1.6 for a 2.0 FE3 motor and boost...the FE3 internals are stronger than the sr20det and can handle incredible amounts of boost