I tried running a single cooler in NorCal - no way. I never tracked it that way, but it didn't work well enough on the street.
If you're willing to make the mods, the center cooler is best. If not, then use 2 fender coolers.
I had 2 fender coolers, and it worked well, even on the track. I was planning to paint my car, and wanted to get an IROC front bumper setup, so I decided to go with a front cooler at the same time. I cut out part of the trunk and made a box for the exit air. I fabbed all mine by hand, but TRE sells a piece for this.
The Carrera cooler with a center cooler works much better (IME) than the 2 fender coolers. I recently had a boo-boo with the IROC front bumper and a curb, so I moved the cooler up 2 1/2", upgraded from AN-12 to AN-16 lines, and switched to a 965 bumper. I also setup to two 2 1/2 shunts for the air to exit to the fender wells rather than under the car. I have no real cooling data available yet; I'll be at Sears on the 6th.
The fins of my my Carrera cooler were plugged up with crap, and it still stayed cool on the track. As an experiement, I want to get a -16 union and try taking the Carrera cooler out of the system to see how well things work.
I seriously considered adding a 3rd cooler - even to the point of purchasing the extra braided steel line - but decided I didn't really need it.
I could make you a screamin' deal on on some -12 line and a Mocal cooler
