BP Lowering Spring Kit - BMW G Chassis

Bimmer Plug’s BP Lowering Spring Kit is a suspension upgrade aimed at BMW G-chassis owners who want a lower stance while retaining the basic usability of the factory suspension. 

What the springs actually change

The key specification is approximately 1.0–1.5 inches of lowering. 

That changes the suspension’s geometry and operating position:

Lower ride height → lower CG → less body movement → sharper transient response

In practical terms:

• Lower centre of gravity — reduces weight-transfer leverage during cornering.
• Reduced body roll — the car feels more immediately controlled during turn-in.
• Sharper turn-in — less initial chassis movement before the tyres build lateral load.
• More aggressive stance — substantially closes the wheel-to-fender gap.
• Greater road contact/control — the manufacturer positions the kit for daily driving and mild-track use. 

The important engineering point

A lowering spring isn’t simply an aesthetic modification.

The spring determines much of the suspension’s vertical wheel rate and ride-height position. Once you lower a G-chassis BMW, the damper operates at a different point in its stroke.

That creates the critical relationship:

Spring rate ↔ damper control ↔ suspension travel ↔ tyre behaviour

If the spring is substantially stiffer but the damper isn’t appropriately matched, the car can become less compliant over broken roads even though it feels more responsive on smooth asphalt.

So for a serious G80 M3/G82 M4, G20 M340i or G22 M440i build, I would evaluate the kit not merely by its advertised drop but by:

1. Actual spring rate
2. Front/rear rate balance
3. Damper compatibility
4. Remaining bump travel
5. Alignment capability
6. Tyre clearance
7. xDrive compatibility where applicable

The product page does not publish those detailed spring-rate figures, so they shouldn’t be assumed from the advertised 1.0–1.5-inch drop. 

BP Springs vs coilovers

Characteristic	BP Lowering Springs	Coilovers
Ride height	Fixed	Adjustable
Installation	Relatively simple	More involved
Cost	Lower	Higher
Street use	Strong fit	Depends on setup
Track setup	Limited adjustment	Much greater flexibility
Damper adjustment	Factory-dependent	Often adjustable
Ride-height experimentation	No	Yes
Wheel-gap improvement	Yes	Yes

The conclusion

The philosophy is OEM suspension refinement rather than a complete suspension transformation.

For a G-chassis BMW that spends most of its life on the street, the BP kit makes sense when the target is:

lower stance + reduced body roll + sharper response without immediately converting the car into a full coilover build.

For a dedicated circuit car, however, the missing variables—particularly spring rates, damper matching and available suspension travel—become much more important than the advertised ride-height reduction.

BP Lowering Spring Kit - BMW G Chassis