The rise of Pirelli World Challenge has arguably been one of the off-season revelations, with the North American sprint race championship set to see a record grid for this weekend’s season-opener at Circuit of The Americas.

A total of 116 cars are entered for the Nissan Grand Prix of Texas, marking a double-digit percentage increase over last year’s numbers. Along with the launch of the new GT Cup presented by MOMO class and the GTS category moving to standalone races, there’s no shortage of storylines.

ENTRY LIST: Nissan Grand Prix of Texas

But perhaps the biggest off-season transformation has come in the flagship GT class, which sees an impressive 40-car field between GT and the GTA subcategory for gentlemen drivers. What’s more, all but two of the cars are FIA GT3-spec, making it second only to the Blancpain Endurance Series in terms of pure GT3 content.

Audi, McLaren, Bentley, Lamborghini, Ferrari, Aston Martin, Nissan, Dodge, Mercedes-Benz, BMW and Porsche are all represented with GT3 cars on the grid, as well as Cadillac with the worldwide debut of its all-new ATS.V-R.

Acura, which makes it 13 different manufacturers in GT, is the only non-GT3 homologated car in the class, with its all-wheel-drive TLX-GT, which features a twin-turbo V6 powerplant derived from HPD’s LMP2 car.

While stalwarts such as Cadillac, GMG and K-PAX Racing have all returned, there’s been an influx of high-profile teams to the paddock, including Scuderia Corsa, Turner Motorsport as well as a new factory-backed Nissan effort led, which have added strength and flavor to the class.

There’s also star power behind the wheel, with former GT champions and factory pilots headlining the driving strength.

Three-time and defending GT champion Johnny O’Connell is back alongside Cadillac teammate Andy Pilgrim, while McLaren factory driver Kevin Estre is set for a full-season campaign in the Flying Lizard Motorsports-run K-PAX squad.

Ferrari factory driver Olivier Beretta will be at the wheel of one of R. Ferri Motorsports Ferrari 458 Italia GT3s, with Chris Dyson and Butch Leitzinger aboard the pair of factory Dyson Racing Bentley Continental GT3s.

Ryan Dalziel steps up to a full-season campaign in EFFORT Racing’s Porsche 911 GT3 R, while Reiter Engineering factory driver Nick Catsburg is set for a championship-seeking effort in a Blancpain-sponsored Lamborghini Gallardo FL2 and Mike Skeen returning to the CRP Racing Audi R8 LMS ultra.

Guy Cosmo has been a late addition to the field, aboard an Audi for M1 Racing and fan favorite Ryan Eversley shouldn’t be counted out either in one of the two RealTime Acuras, which are also competing in the GT class.

There are no fewer than 20 cars set to do battle in GTA, including TRG-AMR’s Christina Nielsen, Henrique Cisneros (NGT Ferrari), Michael Lewis (EFFORT Porsche), Frankie Montecalvo and Eric Lux (DragonSpeed Mercedes), as well as inaugural Nissan GT Academy USA winner Bryan Heikotter.

As a measure to ensure equal competition, GTA drivers who finish on the overall podium will be promoted to the GT category, a measure that was taken twice last year with standouts Andrew Palmer and Nick Mancuso.

The new-for-2015 GT Cup class, reserved exclusively for Porsche 911 GT3 Cup cars, sees an encouraging crop of rising stars, including former IMSA development series standouts as well as existing PWC drivers making the step up from GTS.

Reigning IMSA Porsche GT3 Cup Challenge USA Champion Colin Thompson makes the switch with his Kelly-Moss Motorsports team, while Sloan Urry also transitions to PWC with TruSpeed, which has formed an alliance with the Madison, Wis-based Kelly-Moss squad for 2015.

GTS standout Alec Udell moves to GT Cup in a GMG-prepared Porsche, while Eduardo Cisneros, brother of Henrique, will be at the wheel of a MOMO-sponsored entry from NGT Motorsport, in what is shaping up to be one of the most competitive classes this year.

While GT Cup will run alongside the GT and GTA categories in most rounds this year, the increased fields has resulted in GTS being split into standalone races for 2015, with the TC, TCA and TCB set to continue unchanged this year.

A total of 20 GTS cars are entered for COTA, featuring a diverse mix of machinery including Porsche Caymans, Aston Martins, Ford Mustangs, Nissan 370Zs, Chevy Camaros and defending manufacturers’ champion Kia with its two factory Optimas.

It will be a busy season ahead for all competitors, with a total of 20 rounds on tap for GT/GTA and 18 for GT Cup, GTS and TC/TCA/TCB, which will take teams across the country, a number of events again with IndyCar, prior to champions being crowned at Mazda Raceway Laguna Seca in September.