I want stiffer front torsion bars.

From RPRWiki

OPM Motorsports and Ground Control sell thicker torsion bars made by Sway Away. And the 4WD version of the civic wagon has thicker torsion bars that will fit although they are bit longer than the CRX t-bars. 23mm is probably the thickest you would want for a street driven car, Mugen used to sell a set of 25mm bars and there are bars as thick as 29mm available from OPM.