Wizard exhausts from Autolusso? Just replacing the rear section with a straight through, twin exit such as Ragazzon is nice but not shouty. Not much to it - a custom version would probably be cheaper.
Not sure about your temp gauge thing - must be a reason for the sudden change. I would say normal, ie at normal speed on open road, is sitting about a third around the gauge. as soon as you hit traffic, crawl around town, etc, it rises to just past 90 and then the fan cuts in.
A thought - the fan is supposed to be 2 stage (but never noticed it myself) but this function is very prone to failing due to the resistor breaking. Perhaps that has happened to yours so the first stage does not kick in? just a guess ... plenty of threads on such things.