| SCC did a story about this, wheel wt. vs. chassis wt., about two years ago. I think the ratio they came up with was about 2.0 vs. your 1.6 but I'm not sure.
What everybody failed to notice about Garfields test was he didn't just change wheels, he changed tires, and it was a big change. The Falkens he did his fastest runs on give about the best grip of any street tire out there AND are 23.5" in diameter, much smaller diameter than the factory tires and this made way more difference than the change in wheel weight.
You may want to take a look at the numbers again.
2001 & 2002 SCCA, STS Pro Solo National Champion. 2003 SCCA, Solo2 Nationals 8th, co-driver (Courtney) 2nd in 03 & 04
2003 JCW 210, London Stainless Headers, custom cat back with 5" SuperTrapp, 15x7.5 SSR's and 16x8 ce28n's, Quaife, KW Comp 2 Ways | 
