The BMW G87 M2 is the last of a certain kind of car. A pure internal combustion engined, rear driven, manual optional M car, built in an era that is quietly closing the door on all three. That alone makes it worth getting right.
This guide attracts two kinds of advice in roughly equal measure: breathless hype, and forum folklore. Neither is much use when you are about to spend real money. What follows is the honest version — what to buy, what to leave alone, and how to build a G87 in the right order.
Where do you start when modifying a G87 M2?
Start with the foundations, not the headline parts. Sort tyres, brake pads, fluid and alignment first, then suspension and wheels, then aero, and only then chase power. Mods feed into each other: wheels decide how low you can go, ride height decides which aero survives a speed bump, and power decides what your brakes and tyres have to cope with. Build out of order and you end up redoing work you have already paid for.
Almost every bad G87 build is a good car that someone put together out of order, out of patience, or out of someone else's opinion. Get the sequence right and most of the regrets disappear before they happen.
Watch AUTOID creative director Nathan pick up his G87 M2 and start his first mods.
Know the car before you touch it
The G87 launched in 2023 and runs the S58 — the same 3.0 litre twin turbo straight six as the M3 and M4. There are a few versions worth knowing apart:
- M2 (pre-LCI), 2023–2024 — 460 PS, rear wheel drive, manual or 8 speed auto.
- M2 (LCI), 2025 on — 480 PS, updated iDrive and steering wheel, carbon roof and interior now optional rather than standard.
- M2 CS — 530 PS, around 30 kg lighter through carbon, roughly 8 mm lower on revised springs, dampers and steering. Auto only.
- M2 xDrive — expected from 2026. Not a power model; the story there is traction, not headline figures.
If you are buying specifically to build, the right base matters. Chasing serious power? The automatic's torque ceiling makes it the smarter starting point. After a driver's car? The manual rear drive is the one. Either way, hunt down the carbon roof and the buckets — they are difficult and expensive to add later.
Before you modify anything
The least glamorous chapter, and the one that saves the most money. Before the first part goes on:
- Get the car PPF'd first, so film sits under any splitter line rather than ending at it.
- Fit oil cooler guards and mesh grilles early — the front radiators and oil cooler sit exposed to stone strikes, and that is expensive damage to ignore.
- Take a baseline four wheel alignment and date stamped photos for insurance.
- Keep every OEM part boxed and labelled. Future you, at resale, will be grateful.
- Update your insurance before parts go on, not after.
Styling and aero: choose it as a set
Aero on a road car is mostly about proportion, and the single most common mistake is fitting it bit by bit. A rear wing without a front splitter just adds front end lift. Choose the front, sides and rear as a coherent set, or fit nothing yet.
Material matters as much as shape. Carbon comes in three grades, and only one is really worth building to: pre-preg, autoclave cured and UV stable, is the standard. Wet lay is cheaper and shows it in weave inconsistencies; mixed composites sit in between. Our TREVORA carbon range — diffusers, boot lips and wings for the G87 — is pre-preg for exactly this reason: it holds its finish, and it fits without drama.
One honest note: once you start lowering the car and widening the track, arch-liner rubbing follows. Plan a clearance kit into the build rather than discovering the need on a B-road.
Performance: power is the easy part
The S58 takes to tuning brilliantly, which is precisely why restraint matters. Here is the order that actually works.
Exhaust
Decide what you are buying for. Sound comes from the back box and mid-pipe; the bigger changes — in noise, potential power and legality — come the further forward you go. A quality cat-back such as a Milltek system transforms the character without tipping the car into drone. Anything involving cat or OPF deletes is track-only in the UK and EU, will fail emissions, and should be planned alongside a supporting tune — a de-cat without one throws a catalyst-efficiency warning within a drive cycle or two. Whatever you fit beyond a back box, add a valve controller so you can choose your volume.
Intake
Two separate jobs again: power comes from upgraded turbo inlets, sound comes from the intake cones the factory deliberately silences. Eventuri is the popular choice for good reason; Pro Ram covers the budget end. The old "open intakes kill power through heat soak" line is largely folklore on a road car.
Tuning
A flash tune rewrites the factory ECU — cleaner, more integrated, the most control. A piggyback modifies signals — easier to remove, kinder to warranty and resale. For reference, OEM CS spec calibration alone takes a base car to around 530 bhp, which tells you how much validated headroom exists before you touch hardware. On standard turbos with catless downpipes, the realistic ceiling is around 710 bhp; beyond that you are into built-engine territory.
Cooling
Factory cooling copes with Stage 1 (around 600 bhp) and Stage 2 (around 700 bhp). It only becomes essential at very high power or sustained track use in summer heat. Spend the money where the car actually needs it.
Brakes: the highest-value upgrade nobody photographs
The standard discs and calipers are excellent. The weak link is the pad. Fast road or track pads, braided lines and uprated fluid will do more for how the car feels under you than most things you can bolt on — with no power gain and no warranty drama. Bed them in properly so they don't glaze, and respect the torque figures: rear caliper bracket bolts sit around 110 Nm, but always verify against BMW's TIS data and never reuse single-use fasteners.
Wheels, tyres and stance
The G87 moved to a 5×112 mm PCD with a 66.6 mm centre bore and M14×1.25 bolts — a change from the older 5×120 mm F-series, so older BMW wheels won't fit and any spacers must be hubcentric to 66.6 mm. Factory fitment is 9.5J × 19" front and 10.5J × 20" rear.
For most builds, Michelin Pilot Sport 4S is the right tyre. Lowering is about proportion, not numbers: springs are simpler and cheaper but compress factory damper travel and ride harder; coilovers cost more but keep composure at a lower ride height. Either way, let new springs settle over 100–200 miles before you align, and torque your wheel bolts to 140 Nm in a star pattern with a torque wrench — then re check after 50 miles. Low is a look. Too low is a liability.
The builds that go wrong
The patterns repeat: the over-spacered car, the cheap carbon car, the too low car, the mismatched aero car, the drone-box car, the stretched tyre car, and the big power no cooling car. Every one is a good G87 undone by sequence or by chasing a look in isolation. The best M2s aren't the ones with the most parts. They're the ones where every part agrees with the next.
Three honest starting points
- Tasteful daily — valve controlled exhaust, fast road pads and fluid, quality springs with a proper alignment, a subtle carbon boot lip and diffuser, forged wheels in the correct offset.
- Aggressive street — the above plus a Stage 1 tune, intake, a coordinated aero set, and a careful drop on coilovers.
- Track biased — brakes, fluid and cooling first, then geometry and square wheels, buckets, balanced aero, and only then more power.
The AUTOID perspective
Respect what BMW got right. Sort out what they left on the table. In that order. The G87 M2 is worth building slowly and properly — do that, and you'll end up with something genuinely rare: a modified car with nothing on it you wish you hadn't done.
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