I see conflicting info after a quick search on the calipers. Some say dual, some say 4 piston... Were they ever 4 piston at one point?
I also saw the rotors are 14.3 inches?
That's the second generation 2003-2005 Jaguar STR. The first generation 2000-2002 STR did not have 4-piston brembos. In fact, the first generation was just a 4.2L NA engine instead of the 4.0L NA. The third generationg 2006-2009 STR was still supercharged, but they swapped out some of the more boutique components like the Brembo brake calipers for ones made by regular suppliers. If I am remembering right, the third generation calipers have a lot of similarity with some of the calipers used on Jeeps. I never verified that so no harm no foul.
Rotor diameters were also different between the years.
The 2003-2005 STR was considered the best generation for that model. That's why they are still fairly pricey used.
Using some quick and dirty math, there is about 4% more hydraulic surface area (11309mm2 vs 10897mm2) on the STR caliper pistons. So you aren't loosing anything going to the single piston other then extra wheel clearance. Although I still believe that two pistons react better then one, it has been explained to me that's not always the case.
Again, with some dirty math, there is about 10% more mechanical leverage versus the 320mm brake upgrade I did or about 16% more then the stockers. Not sure how that works out to braking force but there is this crazy engineer guy floating around here who can answer that
