Welcome to the club, Les.
My s type is my second Jaguar. When I bought my first, the salesman told me that I would never drive another make of car. I was unsure of that, not because of the Jaguar, but because I was 76 at the time.
However, he was quite right, and when my X Type 2.5AWD was stolen, I didn't even think of another take of car.
The S type is a very good car, and the 3.0 litre V6 is a great engine, and personally, I would not bother with trying to improve it's performance. Just treat it well, use premium fuel, and make sure it is serviced properly.
I have the 2.7 Diesel SE which is no slowcoach, which I also gave a Terraclean and while it has fierce acceleration, also gives me over 40 mpg and more on long runs.
I hope you enjoy the club and your Jaguar.
Regards,
Peter.