45 HP is enough to take a 13.1 car to 12.5's in the quarter.
It can be argued that people regularly spend that kind of money, and don't see the same performance gain.
Lots of people like to throw around the figure of $10 for every 1 horsepower of gain. The propain system exceeds that somewhat arbitrary figure, at the same time reducing (or greatly elliminating) knock, and providing the convenience of not having to replenish the supply often.
As far as the propane tank in the back, I worry more about the plastic bottle in the front more.
JMO, but the alchy systems should cost more than they do. The correct alchy system would supply a modulated spray (modulated by engine RPM), have 4 nozzles, and a meth resistant pump capable of 60-80 psi. It should be 2 stage as well. A 2 gallon fuel cell mounted in the trunk would be good as well.
A system such as this would cost around $550 - $650 if sold by a vendor. The tuning issues, convenience, and dependably issues would be addressed.
I've only seen one dyno run that involved alchy. It was a while ago but I can say the performance gains were very impressive.
IMO, after considering the information available to me, the propain system is not that much more expensive than a well designed alchy system.
There remain 2 questions that need answering.
(1) Which system holds the performance gain edge.
(20 When will Red Regal T mellow out, and become a peacefull old man...