I put 100hp nitrous in my Ghia about 10 years ago. It was simple and no doubt about the effect. The engine was a well built conservative 1776 type one with all the goodies for 7000-8000 rpm. Never had a problem. I did however use a Jacobs Nitrous Mastermind which probably had something to do with the lack of problems. Had about $1200 into it. Last time I checked you could get a fogger system for about $600? If your engine is strong a 40 hp boost would be pretty conservative/reasonable. Very few moving parts to screw up. If I wanted to go fast, I would do it again in a heart beat.
John
www.ghiaspecialties.com