no 18's, but if you're willing to drop to a 17, falken hanabi's and kosei k1's weigh in at 16 lbs. kosei's are gravity cast, then shot peened, but hard to find since Tirerack stopped carrying them. hanabi's are low-pressure cast (LPC), and I'm not sure about availability.
"The J's weren't designed to be sports cars, the suspension sucks, the brakes are tiny, and the target market for our car doesn't need to be able to do any more than 65mph." - Shifted
A more accurate observation has never been typed. These should be the starting points before any serious performance modification. What's the point of making a serious performer if you can't control it's power?
If you can find a set in a 5x100 bolt pattern try looking for Nippon F2Racing rims in a 16in size. I got mine from discount tire a little over 2 years ago and the rims were listed at 13.5lbs iirc and for the price you can't beat them.
NEED NEW BOLTS TO HOLD KONI'S IN THE STOCK HOUSINGS? I HAVE 10 SETS $5 PLUS SHIPPING