Have you considered the cable mod? It's insane how simple and effective it is at raising the rear by halting the camber movement. I usually run blockers on the street and do this at the track.
Check out the classic weight reduction page by Jamhoney (O.G. guy from the ClubGP days that made a monster 2004 GTP, and got it down to a science by shedding everything he could)... had to use Archive.org since it's now a dead link: https://web.archive.org/web/20120229211624/http://gtpsleeper.freewebpages.org/weightsavings.html
Always wanted to try M/T's drag radials... bought a set for my old GTP, but sold them to another GTP friend in Rochester, NY who loved them. Might look into something for street use, since I put every part possible in the transmission years ago to take the abuse. Have great M/T slicks (3053C) from ~10yrs ago on Weld's that are probably junk now, but I'll just get a fresh set of slicks.
When my GTP started rusting out bad enough, I mothballed the MP112 setup and junked the chassis (*RIP* 10+yrs in NY, MI, OH, WI, MN during college/early work days, incl. ~6 fun winters with snow tires). There's that slick GSX for sale on RegalGS. I'm considering his wrecked car and spare parts, since I don't want to invest in any more FWD's beyond this one.