I just bought a "rallycross ' 2005 Civic (D17- SOHC non-Vtec) from a dude retiring. Very few mods.
Seek your guidance about three suspension matters.
1. Adding a front strut tower brace necessary?
2. I should replace the stock suspension with what? Should I be seeking to raise the height - front and rear?
3. If I get new springs, what should their characteristics be? Spring rate? Etc.?
Yes on strut tower brace, a 3 or 4 point if you can find someone that makes it, spherical compliance bearing, poly bushings everywhere else, eibach sport line or pro line springs, and dont cheap out on struts, kyb or oem Honda, then spend for a nice set of tires. If ride hieght becomes a factor and it needs to be higher with the shorter stiffer springs use a spacer between spring and strut mount.