Laurens Vanthoor and Dirk Werner are among drivers poised to switch GT manufacturers, which will also see the addition of new pilots to both Porsche and BMW factory rosters in the IMSA WeatherTech SportsCar Championship and/or FIA World Endurance Championship next year.

Sportscar365 has learned that Porsche is poised to add at least three new drivers to the fold, with the return of its Manthey-run GTE-Pro program in the WEC requiring an increased factory roster.

Newly crowned FIA GT World Cup Champion Vanthoor is set to switch from Audi to Porsche, potentially as part of its two-car WEC effort.

The Belgian made further hints of his 2017 plans during last weekend’s race in Macau, in the post-qualifying race conference, adding to multiple industry sources that have linked the GT racing standout to Porsche.

It’s understood discussions between Vanthoor and Porsche have been ongoing since this year’s 24 Hours of Le Mans.

Vanthoor is likely to be joined by 2016 Porsche Supercup Champion Sven Mueller as a Porsche factory driver, with the 24-year-old German set to step up to a works seat after three years as a Porsche Junior.

Mueller has already made selected starts in various GT endurance races, including a one-off WEC race at Spa-Francorchamps for the factory squad in 2015.

A persistent rumor of Gianmaria Bruni leaving Ferrari for Porsche, meanwhile, has continued, although it’s unclear if the Italian has actually been signed.

Bruni was courted by the German manufacturer two years ago and is understood to have re-signed by Ferrari for potentially a three-year deal.

More substantiated reports, however, have linked longtime BMW factory driver Dirk Werner with a switch to Porsche, with the former DTM and Supercup pilot potentially taking over a seat in Porsche’s IMSA program.

At least one of Porsche North America’s seats will need to be filled, with 2015 Le Mans winner Nick Tandy set to graduate to a full-time LMP1 drive with the German manufacturer.

Werner’s seat at BMW Team RLL, meanwhile, is likely to be taken up by DTM ace Martin Tomczyk, who along with Canadian Kuno Wittmer, are likely to land full-season drives in the GT Le Mans class next year.

Lucas Luhr is understood to be the other BMW driver on the chopping block, although it’s unclear if the former American Le Mans Series champion will be reassigned to GT3 duties in Europe, ahead of BMW’s ramped up effort in 2018 for its FIA World Endurance Championship debut.

Both Bill Auberlen and John Edwards are set to return to the Bavarian manufacturer next year in IMSA competition, with Nicky Catsburg and Alexander Sims expected to be confirmed as additions to RLL’s Tequila Patron North American Endurance Cup lineup.

The two former 24 Hours of Spa winners are listed to test the BMW M6 GTLM in a two-day test at Sebring next month, with Sims having already sampled the car at Circuit of The Americas earlier this year.

When reached by Sportscar365, a Porsche spokesperson said their lineups, including all new drivers, will be announced at its end-of-year dinner on Dec. 3, with BMW’s lineup set to be confirmed at its Sports Trophy prize-giving ceremony on Dec. 9.