Ring your local roads authority.
If it still has to go over the pits, leave it standard until then. Transport departments don't like welded mods or anything that doesn't look like it belongs there.
However, if you're looking at it for a daily driver as well, you don't really want much more than 1.5 to 2 deg IMHO, otherwise it will a: chew tyres, b: be annoying to drive. I know people are going to say "but I run 6 deg and I don't have issues", well good luck to them. I beg to differ.