Car - Daihatsu Charmant

motor / part in question - 4AGTE exhaust

problem - What diameter

occurs/started when (if applicable)- not yet

personal situation (if applicable)- I like cake


What size piping for a 4AGZ with T25 from SR20? Going to run on AE101 ecu for now and was thinking of 3" down to where the cat
would be normally but would I keep it 3" all the way back or would there be an advantage in stepping down the pipe size to say 2 1/2" to the silencer box?
Also as a road car I don't want it to be silly loud.
Thanks.