Here is Mazdas published wt/yr/hp for NA/NB excluding MSM. Remember, not all the weight gain is fluffy stuff, some is structural and performance improvement.
Year Wt. HP lb/hp hp/lb
1990 NA 1.6L 2182 116 18.81034483 0.053162236
1991 NA 1.6L 2182 116 18.81034483 0.053162236
1992 NA 1.6L 2214 116 19.0862069 0.052393857
1993 NA 1.6L 2223 116 19.1637931 0.052181736
1994 NA 1.8L 2293 128 17.9140625 0.055822067
1995 NA 1.8L 2293 128 17.9140625 0.055822067
1996 NA 1.8L 2293 133 17.2406015 0.058002617
1997 NA 1.8L 2359 133 17.73684211 0.056379822
1999 NB 1.8L 2299 140 16.42142857 0.060896042
2000 NB 1.8L 2332 140 16.65714286 0.060034305
2001 NB 1.8L 2387 142 16.80985915 0.059488898
2002 NB 1.8L 2387 142 16.80985915 0.059488898
2003 NB 1.8L 2387 142 16.80985915 0.059488898
2004 NB 1.8L 2447 142 17.23239437 0.058030241