At the risk of exposing my hard math deficit, I'm thinking that 250 is the outside you would want with a 25.5 torsion bar, sans rear coil-overs. Not that the factory settings are the end all but the boys from Stuttgart moved the front springs from about 125 lbs to 175 lbs when then went from 23.5 to 25.5 on the torsion bars. I have Jason prescribed 200 lb Weltmeisters on the front of my NA autocrosser and they balace quite nice with 23.3 and a 19 mm rear factory bar.

If you pay that 75 lbs of extra front spring forward to a 25.5 you get 250 as compared to the OE 175. Make sense?