Aquamist and snow performance both used to market Naturally Aspirated kits.
You could check Ebay for one of the older Edelbrock kits.
As I understand it though the newer higher pressure kits work better due to finer atomization of the water.
Yes, the newer systems have up to 250 psi,the old Edelbrocks are just basically a windshield wiper pump,low pressure.
The newer systems are much better.
http://www.alcohol-injection.com/water-injection-kits-1/chevy-20/camaro-97/MBHD
