Yeah the holidays snuck up on me and I coud see the extra 5-7 pounds every time I fastened the seat belt. REPULSIVE.
In a momment of desperation (too cold to get the Bianchi out) i ordered one of those ab chairs from home shopping network. LOL But the ability to stetch out my back on that thing after sitting in that GT3 seat is addictive! I have a congenital back defect (tail bone fused to 1st v.) Beats Roman chair sit ups by a mile.
anyhoo, I'm Assuming you ordered black seats. I saw a guy on Rennlist with a really nice set of Simpson belts in Silver(1-800-654-7223). I think they are cheaper than the Schroths (which Porsche rebadges as their own).) The Simpsons are the Platnium series cam lock 6 pt. harnesses with 3" lap belts and 2" sub belts. Make sure to get the "pull up" and not pull down. Hard to adjust the pull downs.
In the meantime you can use the CG-Lock for Autocross. They have a great installation guide on the site.
http://www.cg-lock.com/
from a driving point of view my Toyo RA1's and those seats were the best mod to date. You'll have to get used to sitting lower, you'll drop a couple of inches.
p.s.
You'll need a set of
reverse torx sockets to fasten it to the floor. that delayed my installation as I waited the bits to come from mail order, ebay if I remember.