Lifestyle is directly proportional to income. If you have a $1M income, you will have a $1M lifestyle. If you have a $25k income, you will have a $25k lifestyle.
This is not to say one is better than the other, just that income and lifestyle are normally linked. You do get exceptions (millionaires living on the street, etc - people embezzling money to live like millionaires), but for the majority, lifestyle is income driven.
To own a Porsche, even an old one, you need to most likely be of above average wage in terms of income (or live very frugally if below average). Then it all comes down to how much disposable income you have left over, and what choices you make with that.
Some may be timing, in that, with kids at school, etc - when they finish in a couple of years may free up income for other activities.
So, firstly, you need the desire. From all of the posts, there are lots of 968 Forums members who desire a faster car and the supercharger kit. Then you need the surplus income and the desire to push you towards buying it. Then you need the desire, surplus income and no competing demands for the spend and approval from the significant other, plus the desire to install it or funds to get someone else to do it, possibly plus the desire and funds to do any other outstanding engine maintenance, etc. everytime you go through one of these "and" gates, you are dropping around 50% of the population of Porsche 968 owners. So, with around 5 to 6 combined "and" gates, the progression goes,
50%, 25%, 12.5%, 6.25%, 3.125%, etc.
So around 5% is not bad.
I think that once the performance, reliability and ease of installation (or accuracy of installation) gets known, and the car gets older - installs would increase.