The AWD Swap PI Debate: Everyone Arguing Is Partly Right

TL;DR

A r/ForzaHorizon post showing the Huracan STO’s drivetrain swap screen set off the biggest tuning argument of the Series 3 stretch. The AWD swap preview drops the car’s top speed from 313.8 km/h to 277.9 km/h.
The claim: the AWD swap ships its own short-geared gearbox, PI gets calculated on that default, the game scores the car as slower, PI drops — and then you tune the gearing back and keep the discount.
The top-voted reply disagrees with the mechanism, not the outcome. Two other regulars offer a third and fourth explanation. None of them are obviously wrong.
Here’s the part that resolves it: PI is a five-factor formula, and AWD pushes different factors in different directions depending on the car. That’s why the thread can’t agree — and why the swap adds PI on some cars and removes it on others.
What’s genuinely documented is narrower than any camp claims. And the follow-up campaign to rework PI drew real pushback — 71 upvotes against 20 downvotes — but the objectors mostly agree the system is flawed. They’re arguing a rework won’t deliver what people want, which is a different thing entirely.

What the screenshots actually show — and what they don’t

The post that started it is straightforward. A 2020 Lamborghini Huracan STO, no upgrades, stock tune, sitting at S1 783. On the Drivetrain Swap screen, the stock setup reads 0–97 km/h in 2.900s, 0–161 km/h in 6.083s, and a top speed of 313.8 km/h. Highlight the 10,000 CR AWD swap and the preview changes: 0–97 drops to 2.517s, 0–161 to 5.683s — both quicker — while top speed falls to 277.9 km/h.

Faster off the line, nearly 36 km/h slower flat out. That’s the AWD swap’s bundled gearbox doing its work.

Be precise about one thing, because it matters: the PI counter reads 783 in both shots. The swap isn’t installed in either — the second screenshot is still on the “Buy and Install” prompt. So the images document the gearing delta, not a PI change. That doesn’t make the argument wrong; the gearing difference is real and it’s the thing the post is pointing at. It just means the screenshots alone don’t prove the conclusion.

What PI actually measures — the part that isn’t up for debate

This is where the thread would have saved itself a lot of trouble.

Per the Forza Wiki’s Performance Index entry, PI evaluates five performance factors, each scored from 3.0 to 10.0:

Speed — top speed, determined by engine performance and transmission gearing
Handling — maximum cornering speeds, from lateral G at 97 km/h and 193 km/h
Acceleration — 0–97 km/h and 0–161 km/h times
Launch — acceleration from a standstill, over those same two benchmarks
Braking — stopping distances from 97 km/h and 161 km/h

There’s also a Class rating derived from a simulated test-track lap. And critically, the same entry states it plainly: “Performance Index values can be altered by applying Upgrades to cars but cannot be changed by custom tunes.”

So the foundational claim in the original post — that the game scores your car on the default configuration and never revisits it when you tune — is not a theory. It’s documented behavior, and it has been how Forza works since Motorsport 2. Note also that Horizon keeps Launch as its own separate rating; the modern Motorsport titles dropped it.

Hold onto that, because it’s why all four explanations below can coexist.

Explanation one: the gearbox drops the Speed score

The original argument, from u/Martin_Sandman, runs like this. AWD swaps come with their own gearbox and notably short gears. Top speed feeds the Speed factor. Lower top speed, lower Speed score, lower PI. The gearbox is fully adjustable afterward, so you stretch the ratios back out, recover the top speed, and the game never rescores you.

“Forza calculates the performance index using the default tune, that is the slider position after freshly equipping parts. The game never acknowledges these can be modified and so the PI remains the same even after changing everything.”

The documented formula supports the mechanism — gearing genuinely is an input to Speed, and tunes genuinely don’t rescore. Where it gets contested is whether that input is doing enough of the work to explain the size of the drops people report.

Explanation two: it’s launch traction and wheel diameter, not gearing

The most-upvoted reply in the thread, from u/talhaONE, rejects the gearbox story outright:

“contrary to popular belief the current broken AWD swap isnt caused by the AWD swaps stock transmission settings. PI system isnt that dumb, it doesnt decrease PI from transmission when its fully adjustable.”

Their alternative has two parts. First, tire slip on launch: if a car already launches cleanly in RWD with minimal wheelspin, the system reads the AWD swap as adding weight without adding usable traction, and discounts it accordingly. That’s why they name the Ford GT and Lamborghini SCV12 as the worst offenders — both launch well stock — and why drag tires cost a lot of PI on RWD but very little on AWD.

Second, wheel diameter mismatch: they argue the system treats a front/rear diameter difference on an AWD car as understeer and over-discounts for it. Their suggested test is a pickup — take the Mercedes X-Class, raise the rear tire profile, and watch PI fall further than it should. Do the same on an RWD-swapped X-Class and the effect disappears.

Epistemic status: this is community inference, not published data. It’s testable and the proposed test is specific, which is more than most tuning folklore manages. But nobody has posted a systematic sweep.

Explanation three: the game punishes default understeer

A third account, from u/TTR_Coco, agrees PI ignores tunes but says both camps above are chasing the wrong factor:

“top speed is VERY rarely the limiting factor on PI… the real reason AWD swaps are good for SOME RWD cars is very simple: default understeer.”

The argument: Forza’s default tunes are poor, aggressive anti-roll bar splits are the main way to buy rotation, and an AWD swap makes the stock understeer worse. Because the formula weights Handling more heavily than Speed or Launch, a car that understeers badly on its default tune scores low — and hands you the PI back. They also note the long-running road Rivals pattern of very high-horsepower RWD builds, where the game struggles to price power the driver can actually deploy through gearing and pressure adjustments.

If you’ve read our tuning reference, this should sound familiar — it’s the same reason the 1/65 anti-roll bar split works on circuit AWD builds in the first place.

Why they’re all partly right — and the thread never noticed

Here’s the resolution nobody in that thread quite reached.

Speed, Handling, and Launch are three separate factors in one formula. An AWD swap moves all three at once, in different directions, by different amounts, and the amounts depend entirely on the car:

It lowers Speed on anything where the bundled gearbox shortens the ratios — most pronounced on cars with high stock top speeds, which is exactly the supercar bracket the original post is drawn from.
It raises Launch — but only meaningfully on cars that were struggling for traction. On a car that already launched cleanly, there’s little to gain, which is talhaONE’s point.
It hurts Handling on the default tune by adding understeer and front-axle weight, which is TTR_Coco’s point.

Whether the net comes out positive or negative isn’t one answer. It’s per-car arithmetic. That is precisely why the thread splintered — and it explains the flat contradictions in the replies better than any single theory does.

The part nobody has settled: how often does it actually happen?

This is where the thread gets genuinely unresolved, and it’s worth being honest that it stays that way.

Several experienced players dispute that PI drops are common at all:

u/LickMyThralls: “It adds pi like 95% of the time,” and reports their Jesko losing PI when swapped from AWD to RWD — the opposite direction.
u/Moist-Length1766: “in all S1 and S2 cars, I haven’t seen a single car DROP PI if you swap it to AWD.”
u/Icy-Extreme9067: true for most modern RWD cars, but AWD increases PI on “95% old RWD cars, every FWD, and manual cars.” Also notes you can recover lost PI by fitting a race gearbox, which pushes the stats back up.
u/BothCall8395 offers hard counterexamples: the Dodge Dart runs 540 to 594 on the swap — a 54-point penalty, and they rate it the worst value in the game — while the Ferrari 599XX Evolution moves by exactly 1.
u/thomas-grant notes the behavior changed between FH5 and FH6, which would explain why veteran intuitions conflict.

Against that, the original poster maintains they’ve seen multiple supercars drop by large amounts in S1 and S2.

No one has published a systematic survey. Until someone sweeps the car list and posts the numbers, “how common is this” is an open question, and anyone stating a percentage — in either direction — is estimating.

The case for leaving it alone, which deserves a fair hearing

The obvious fix is “calculate PI from the actual tune.” It has a real problem, and u/HazuniaC put it well:

“It wouldn’t make sense to compare custom gear ratio values as this would allow some pretty insane shenanigans with extremely short gearing to give you more PI roof. Enter an event at 600 PI and revert back to regular gear ratios in the event, so suddenly you have a 800 PI rated car.”

That’s not a hypothetical. Scoring PI on a live, editable tune creates a straightforward exploit unless the game also locks tunes at event entry. The current design — score the fixed thing, let players adjust the flexible thing — is a defensible answer to a hard problem, even if the default values it scores against are badly chosen.

Which points at the middle path several people landed on: keep scoring defaults, but fix the defaults. If the AWD gearbox shipped with sensible ratios instead of unusually short ones, the Speed discount would mostly evaporate without opening the exploit door.

The rework debate isn’t “fix it” vs “don’t” — it’s about what fixing it buys you

A day after the Huracan post, u/Armroker put up a second thread pushing people to upvote the PI rework ticket on the Feedback Portal, arguing that Playground applies “band-aid fixes, like nerfing whatever OP car is abusing the system the most at the time” rather than addressing the root cause.

That post sits at 71 upvotes against 20 downvotes — a striking amount of pushback for a “this thing is obviously broken, go vote” post in a subreddit that had just spent a day agreeing the PI system is strange.

Read the objections closely, though, because this is the part that gets misreported. Almost nobody in that thread is defending the current formula. They’re disputing what a rework would actually accomplish. That’s a different argument, and a more interesting one.

u/Hircine_Himself makes the point most explicitly — first the skepticism:

“Even if adjusting the PI system itself gets reworked, you can bet your ass that for all the meta cars that get hit by it, new ones will rise to take their places.”

and then, plainly: “I’m not saying balance shouldn’t happen, I just don’t know the answer, myself.” That’s not opposition. That’s someone who agrees the system is flawed and doubts a rework eliminates the thing people are actually angry about. Any competitive game with distinct vehicles will produce a dominant build; you can move which car it is, not whether one exists.

u/stormwalker29 lands the strongest practical objection — and then votes yes anyway:

“They won’t do it, because it would blow up potentially every tune in the game. If they were going to do it, they needed to do it between games.”

“That said, I’ll still vote for it because they need to know that we are unhappy about it and at a minimum want it fixed in the future.”

Reprice the formula mid-lifecycle and every shared tune, every Rivals time, and every carefully built garage gets rescored overnight. Their read is that the window closed at launch — so the vote is a signal for the next game, not a request for this one.

u/numarkzz is firmly on the pro-rework side and articulates the actual grievance well: some cars “clearly belong in a higher class,” lobbies are “plagued by Honda Beats and V10 sounds,” and “it’s not about driving skill anymore, the car is all that matters.” u/Snack29 adds the sharpest framing of all: “most online multiplayer games receive balance patches over time. but for some reason racing games are considered exempt.”

Genuine opposition is thinner than the vote count suggests. u/kokosgt calls it “the least important” of Forza’s multiplayer problems and u/Vexxed14 offers a flat “No thanks” — but those are the outliers, not the body of the dissent.

The one objection that isn’t about tactics is u/Grey1251’s, and it’s four words: “How do you balance reality?” Forza’s cars are licensed reproductions with real performance figures. Any system that sorts them into classes is an approximation of something that was never designed to be balanced.

Worth flagging one factual thread within it. u/CSL_M3 claims Playground has never directly nerfed a car in a Forza game; Armroker responds that nerfs happen quietly “by decreasing hidden stats like torque multiplier or aerodynamics.” Neither claim is sourced, and we haven’t been able to verify either — treat that exchange as unsettled.

One more piece of rhetoric to discount: Armroker’s line that “9 out of 10 players prefer Spec Racing.” That figure is rhetorical, not measured — and Hircine_Himself pushes back on the premise anyway, on the grounds that building your own car is the point of Horizon. u/glue010 offers the compromise worth stealing: Spec events restricted to a group of eligible cars rather than a single model.

And if you do want to vote, know what you’re signing up for. Multiple commenters flagged real friction with the Feedback Portal: it requires a separate account, asks for your full name — Playground’s guidance in pinned tickets is to use your in-game name — and reportedly logs you out at random. That’s a low-grade barrier, but it’s a real one, and it’s part of why ticket vote counts run lower than subreddit sentiment would suggest.

What this means for your builds right now

Practical, regardless of who’s right about the mechanism:

Check the swap on your specific car, not on advice. Given the per-car arithmetic, general rules are close to useless here. Note the PI before and after, in the upgrade screen, on the car you’re actually building.

If PI drops, the gearing is worth revisiting. The Speed score was calculated against ratios you’re not obligated to keep.

Don’t assume AWD is the answer everywhere. Our post-drag-tire-nerf touge testing found well-tuned lightweight RWD back on top on technical mountain roads, even while AWD continues to dominate S1 and S2 road Rivals. Both things are true at once — they’re different disciplines with different corner profiles.

Old, low-power, FWD, and manual cars are the ones most likely to bill you. That’s the one point of broad agreement across the disagreeing camps.

The bottom line

The interesting thing about this argument isn’t who wins. It’s that a five-factor formula, scored once against default values and never revisited, produces behavior that experienced players cannot reverse-engineer by consensus after four hundred-odd comments. Two of them ran opposite experiments on a Jesko and got opposite results.

That’s the actual story. Not “AWD is broken” — the fact that the pricing system for every competitive lobby in the game is opaque enough that its most invested players disagree about which direction it moves.

Playground has already shown willingness to reprice things when the data is clear: B-Class AWD swap costs were raised specifically to stop an AWD meta forming in the lower tiers. Whether that extends to a full formula rework is the open question — and note that even the skeptics mostly want it fixed. Their case is that a rework rescores every tune in a live game, and that a fairer formula still produces a meta, just a different one. Both of those are true. Neither is a reason the current defaults have to stay as bad as they are. The ticket is FH6S-5878.

What isn’t in dispute is the information gap. Nobody has swept the car list. Both threads ran hundreds of comments on a question that a spreadsheet would settle in an afternoon.

So go check one car you actually race. Note the PI stock, note it swapped, and post the pair — in the ticket, in a thread, anywhere. That single data point is worth more than another round of the argument.

Sources: r/ForzaHorizon — the AWD swap PI thread, with thanks to u/Martin_Sandman, u/talhaONE, u/TTR_Coco, u/HazuniaC, u/Icy-Extreme9067, u/BothCall8395, u/LickMyThralls and u/Moist-Length1766 · r/ForzaHorizon — the PI rework vote thread, with thanks to u/Armroker, u/stormwalker29, u/Hircine_Himself, u/Snack29, u/kokosgt, u/Grey1251, u/CSL_M3, u/numarkzz and u/LeftPersonality · Forza Wiki — Performance Index · Forza Feedback Portal — FH6S-5878

Vote counts and quotes reflect both threads as of 12 August 2026 and will have moved since.