Do the 95 Se'* have 2.25 or 2.5 inch exhaust piping :?:

you have to go ame mesaure it yourself, some have 2.25 and some have2.5, i would have to guess 2.5

i've got 2.25

My guess would be 2.25 if it'* an SE without the SLE package, but since GM never does anything with much consistency with these cars it is just a guess. An exhaust shop would be able to tell you for sure.
Is there an RPO that will tell what diameter pipe a car has?

no RPO of find out what is on there, but JR'* seemed to have the 2.5 on his 95