Pfaff Motorsport driver Jaminet held off repeated challenges from fellow factory Porsche driver Vanthoor's KCMG machine, which was making a one-off appearance in the IMSA SportsCar Championship season opener, to win alongside Matt Campbell and reigning IMSA Daytona Prototype international champion Felipe Nasr.
The pair were frequently side by side over the closing three hours and were initially able to stay clear of the chasing Risi Competizione Ferrari.
But contact on the final lap approaching the newly-renamed Le Mans Chicane caused both to get sideways, with a disconsolate Vanthoor spinning across the grass and dropping to second behind the Alessandro Pier Guidi-driven Ferrari.
“These last two hours have been maybe the most stressful of my life,” said Jaminet.
“What a crazy fight with Laurens. We all know how good he is, one of the best GT drivers out there in the world.
“We had a great fight. It was sometimes on the limit, maybe even over.
“In the end we took care, let's say, and tried to make it to the end, even though we had some small contacts. Last chicane was kind of crazy.”
Vanthoor said: “Our goal for this race was to win it.
"I literally tried everything I could imagine to overtake the Pfaff car but it was not enough.
"We can be proud that we tried everything but unfortunately it was not enough today.”
GT3 debutante Nasr paid tribute to his Pfaff team on his first race outing for Porsche since signing for the Weissach manufacturer to race its LMDh prototype in 2023.
The ex-Formula 1 driver, who will contest the four endurance rounds of the 2022 season, said the experience of racing a GT car put him "out of my comfort zone".
"This transition from the DPi to GTD Pro was probably one of the most challenging things I've done in the last few years, getting out of my comfort zone - I was so used to the DPi," said the Brazilian.
“I have to say everybody within Pfaff Motorsports, two incredible team-mates, they helped me through every session, through every kind of procedure. Every time I was out in the car, had more laps, I just felt very comfortable.
“I've been very close a couple of times at this race, but finally being able to win it feels incredible.
“I just want to thank those guys for the opportunity in my first-ever race for Porsche as well. Couldn't have gone a better way of starting this relationship."
