Rear diffusers, spoilers and canards: how they differ and which to fit first
These three rear-end parts are often lumped together as the aero kit, but they do different jobs with different results. This page explains what each does, which changes the look most, and the order that avoids redoing work later
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The three parts work in different places
The diffuser sits under the rear bumper. In principle it manages air leaving the underbody; on normal roads the aerodynamic effect is barely felt, but the visual effect is strong because it makes the rear look lower and wider
The spoiler sits on the boot lid or roof edge. Small lip spoilers are about looks and tidying the rear; large wings only start working at genuinely high speeds, beyond normal road use
Canards are small fins at the bumper corners, fitted mainly for an aggressive look, and the cheapest of the three
The order that avoids redoing work
If the goal is to change the rear-end character, start with the diffuser: it changes the rear proportions more than any single part, and it decides where the exhaust tips come out
If you also plan to change the exhaust, decide on it together with the diffuser, because the position and number of tips must match the diffuser openings — otherwise you end up modifying and wasting parts
The spoiler can go on later without affecting anything; canards should go last, after you see whether the rear already looks full enough
Adhesive or drilling?
Most diffusers and canards mount with high-grade double-sided tape plus hidden clips. With good surface prep they last; the usual problem is sticking onto a surface with leftover coating, so the tape does not hold
Some large spoilers need drilling, which cannot be undone. If you are not sure about the look, start with a tape-mounted one
Choose by the result you want
| You want | The part for it | What to check alongside |
|---|---|---|
| A lower, wider-looking rear | Rear Diffuser | Exhaust tip position |
| A tidier rear silhouette | Lip spoiler | Body colour and mounting method |
| A more aggressive look on a budget | Canards | Ground clearance |
| Better engine bay and wheel arch cooling | Air Vents | Where drilling is actually possible |
Frequently asked questions
Does a diffuser really improve grip?
At normal road speeds there is hardly any felt effect; these parts are designed to work at much higher speeds. Most people fit them for the look, which is the more honest reason
The stock exhaust does not line up with the diffuser openings — what now?
Two options: change the tips to match the openings, or choose a diffuser made for the stock exhaust. What not to do is enlarge the openings yourself — the edges will be rough and obvious
Do all large spoilers need drilling?
Not all. There are tape-mounted and drilled types. Drilling is more secure for big wings, but if removed later it leaves holes to fill and paint
Will canards make the car scrape?
Canards sit at the bumper corners, higher than the front lip, so they normally do not add scraping — but if the car is already lowered, measure first
Is price the only difference between carbon and ABS?
They differ in weight, surface and repair. Carbon is lighter and shows its weave, but a scrape into the fibre is hard to repair invisibly; ABS is painted over and far easier to repair
Where does this information come from?
Written from the products we actually import and sell, not translated from foreign sites. Item counts are read live from this site's product database when you open the page — there are currently 42,317 products in the system, and the numbers here update automatically
Flinstone Autoparts imports and installs car tuning parts, with 2 branches in Bangkok — Sathorn and the Ekkamai–Ram Intra expressway frontage road
Other guides: Chassis code · Front Grille · Silicone Hoses · Intake system · Headlights & tail lights · Android screens & tuning boxes · Interior Trim
