Mark i made about a doz. restrictor plates on the CNC mill for Jimmy Smiths 7.00 index car, running a 750 holly. His car would run 6.60's. I used 1/32" alum and made them in 1/32" increments, he could slow it down to 7.10's with the plates, but as the temp. changed at nite he would still have to add weight to hit the numbers. He won lot's of money by running the plates and they didn't hurt the 60' times.
JMO
Zip.