Next year's American Rally Association presented by DirtFish technical regulations have been finalized following lengthy consultation between ARA, its teams and its competitors.
As announced back in May, next year's Open 4WD class cars will be scaled back, bringing them more in-line with the FIA's global Rally2 formula.
That means that the Subaru WRX STIs Subaru Motorsports USA runs and the Hyundai i20 Coupe WRC that Hoonigan Racing Division has fielded this year will both be ineligible to compete in the ARA from 2023.
While there are no radical changes from the technical regulations proposed earlier this year, some subtle areas have been tweaked, including new restrictions to simplify aerodynamic modifications and also a reduction in turbo size from a 34mm to 33mm restrictor in O4WD.
"The biggest change in the rules are really in the Open classes, specifically the Open 4WD bodywork changes and some power changes," explained ARA competition director, Preston Osborn.
"The big takeaway is the bodies are going to be much more simple as far as aerodynamics go. As exciting as the cars have looked in our series with some really exciting competition this year, really the feedback from a lot of teams has been that it's not sustainable.
"Aerodynamics are exceptionally expensive to develop. The bodywork becomes very intricate so even the body pieces themselves are very expensive, so we've really worked to simplify that with the target being we want the O4WD class much closer to the Rally2 and RC2 cars that we've seen competing internationally worldwide.
"We've really done work to equalize those classes, so while they are a separate set of rules the performance potential of them should be very close."
Changes aren't limited to O4WD though, as from next year the vehicles in Limited 4WD will also need to run a 33mm restrictor.
"We have been looking at the data and seen the speeds, it's really been a bit of a power creep," said Osborn.
"So in L4WD, especially with 36mm restrictors, the horsepower those cars are capable of was maybe larger than expected when that rule was originally put in place so it's kind of bringing those in line with the modern power targets that we're shooting for.
"So those will also be a 33mm restrictor."
Another key change in the L4WD category is the introduction of Rally3 cars, which so far have been forced to compete in O4WD and simply been outgunned by the more powerful, far less restricted machines in the class.
Osborn said: "As the Rally3 cars have started to compete worldwide we weren't quite sure how and when we'd start to see them here in the US, and we've gotten more interest than expected with those cars coming in.
"It's still not quite to the point where we can have them as their own class or their own cup, but looking at the performance potential of those cars they're pretty similar to what we have with our L4WD cars now and so they'll compete within that class.
"Of course they have to stay within the FIA rules to compete as a Rally3 car, but as long as they meet those homologation rules they can compete in L4WD."
Finally, those competing in any of the ARA Regional championships - ARA Central, ARA East or ARA West - will have longer to make their cars comply with the new technical ruleset due to the smaller budget of the competitors.
"We are of course mindful of the Regional classes, and we know their budgets are a bit different so we are giving them a year's leeway," Osborn reasoned.
"So in 2023 the Regional classes can run their restrictors as they are currently, and then 2024 they'll be the same as National classes."
All of the ARA's technical documents and regulations can be viewed in the 'Rules and Bulletins' section of the website.