Aprilia RS 660 mods & upgrades

The RS 660 landed with RSV4-grade electronics, a MotoAmerica Twins Cup grid waiting for it, and a race-parts ecosystem that showed up within a season. It's the modern answer to 'one middleweight for street and track' — and almost nobody's stays stock past the first month.

1. Clean the tail

   Fender eliminator and flush signals — the stock plate hanger is the first thing every owner deletes. Bar-end mirrors are a common follow-up; the stock mirrors are a running complaint.

   Tail Tidy & Billet

2. Protection

   Frame sliders and engine case covers. Twins Cup supply means good coverage: GB Racing and Woodcraft both list the 660, and US race vendors like Spears Racing stock 660-specific protection.

   Crash Protection

3. Slip-on

   The SC-Project CR-T is the signature RS 660 pipe (it's what the Extrema wears); Akrapovič and LeoVince cover the other price points. Slip-ons keep the mid-pipe cat, so they run fine without a tune.

   Exhaust

4. Levers and grips

   Shorty adjustable levers (ASV, CRG) and tank grips. Cheap no-name levers are a recurring gamble in 660 owner threads — buy once.

   LeversClip-ons & Throttle

5. Tune when the cat goes

   A full decat system without a tune means a check-engine light. If you're going full system, budget the flash with it — that pairing is where the twin's midrange fills in (community consensus, not a dyno promise).

   TuneExhaust

6. Spring for your weight

   The base KYB fork and stock shock are budget-grade and sprung for a light rider. Springs matched to your weight transform it; full cartridges can wait for track duty.

   Suspension

1. Tires

   Supercorsa SP or Q5 on the stock 120/70-17 and 180/55-17 sizes. The chassis is honest enough that rubber is the whole first step.

   Tires & Wheels

2. Brake consumables

   Race pads, braided lines, fresh fluid, lever guard. The stock Brembo radials are good hardware — feed them better pads before touching anything else.

   BrakesCrash Protection

3. Suspension

   Cartridge kit and shock, sprung for your weight — Öhlins and K-Tech both catalog the 660, and Twins Cup teams have published baseline setups. 2025 Factory bikes arrive with Öhlins already.

   Suspension

4. Ergonomics

   Rearsets (Bonamici and Woodcraft are the Twins Cup picks) and adjustable clip-ons. Budget eBay rearsets on this bike are a documented community gamble.

   RearsetsClip-ons & Throttle

5. Make it crash-able

   Case covers, axle sliders, race bodywork. 660 race fairings are widely available thanks to Twins Cup — but 2025+ winglet bodywork is its own fitment.

   Crash ProtectionBodywork

6. Full system, tune, gearing

   Full exhaust with a matched flash, then gear it per track — stock gearing is tall for tight circuits and a rear sprocket change is the cheap fix.

   ExhaustTuneDrivetrain

• RS 6602021–2024

  Launch generation: ~100 hp claimed 270° twin, full APRC electronics with bidirectional quickshifter standard, KYB fork and adjustable monoshock (Aprilia's 2020–2023 spec sheets do not name the shock maker; the 2025 sheet says Kayaba), Brembo radial calipers. Early 2021 builds fall under the con-rod recall (NHTSA 21V-502) — affected engines were replaced whole; verify by VIN.

• Extrema2023

  Limited edition: SC-Project silencer, carbon bits, solo-seat tail. Chassis and most parts fitment track the standard 2021–24 catalog.

• 2025 refresh2025–present

  ~105 hp claimed via 52 mm throttle bodies, new fairing with integrated winglets, launch control added; new Factory trim ships Öhlins NIX30 fork and STX46 shock. Bodywork and screens from 2021–24 do not fit.