A total of 22 all-pro entries will be on the grid for the oversubscribed Blancpain Endurance Series opener at Monza this weekend.
The Pro Cup makes up more than one third of the 62-car entry for the three-hour race at the home of the Italian Grand Prix on Sunday. The 22-car total compares with the 11-13 Pro cars that turned out in the five three-hour rounds of the series last year.
Series boss Stephane Ratel, who has cut back the series from six to five rounds for this season, said: "This is unbelievable. This is a sign that the series is becoming more and more competitive.
"In all the championships I have organised over the past 20 years, only once have I had more than 20 all-pro cars and that was in the first year of the FIA GT1 World Championship in 2010."
The Pro Cup entry is led by the WRT Audi and Marc VDS BMW teams, which battled for last year's BES title, with three and two cars respectively.
Phoenix Racing, winners of last year's Spa 24 Hours round of the series, also fields a pair of Audi R8 LMS ultras, while Vita4One has two BMW Z4s, down from the planned three, on the entry.
Hexis Racing, a front-runner in the defunct FIA GT1 World Championship, leads the McLaren attack with a pair of MP4-12Cs, one in the Pro Cup and one in the Pro-Am category.
JRM Racing also has two entries for the Nissan GT-R NISMO GT3 it has jointly developed with the Japanese manufacturer, one in Pro and one in Pro-Am.
BMW, McLaren and Audi all have factory drivers in the BES: BMW is represented by Maxime Martin (Marc VDS); McLaren by Alvaro Parente, Alexander Sims (both Hexis), Rob Bell and Adam Carroll (both Gulf); and Audi's roster of drivers includes Oliver Jarvis, Markus Winkelhock (both Phoenix), Stephane Ortelli and Rene Rast (both WRT).
The rest of the grid is split between the Pro-Am Cup and the Gentlemen Trophy class.