Engine:

• New Digital control box raises redline to 9800 rpm
• New crankshaft with more oscillating mass (removable) offers more traction and better handling

Exhaust:

• New single-tube exhaust pipe, reshaped main silencer, ovalized inner chamber for greater torque (smaller and lighter like 450 SX 2003)

Frame:

• High-end chromoly frame features reduced wall thickness and lower overall weight – total frame weight now less than 9 kg (20 lbs.)
  
• New forged swingarm support and footpegs similar to 250 SX 2003 result is narrower, flatter profile and reduced weight
  
• Reinforced steering head area affords more reliability

Swing arm:

• Swing arm pivot increased 2 mm to 17 mm diameter (stiffer and lighter weight)
  
• 10 mm longer in all 2004 models offers more traction and more room for the rear wheel

Fork:

• Newly adjusted WP 48 mm USD fork features three bushings –fork is more supple and offers greater sensitivity

Shock:

• Improved sensitivity and increased bottoming resistance through use of an optimal setting and a linear wound main spring

Front Brakes:

• All SX models have new brake discs with round holes for weight reduction, less wear and reduced operating temperature

Rear Brakes:

• All models have the same foot brake-cylinder (integrated reservoir) and the same brake calliper (26 mm) as 250 SX 2003

Wheels / Tires:

• Excel Rims
  
• Bridgestone M 59 and M 70 tires

Body Work:

• One-piece rear fender / side panel combination – same as last year's 250 SX and 450 SX – for all models
  
• Lower sub-frame assures optimal handling
  
• All seats feature a new seat base, anchored by a single mounting bolt located underneath the seat
  
• New larger airbox to accommodate one-piece tail section

Instruments / Controls:

• Renthal 608 tapered handlebar (12 mm higher than last year)
  
• Clutch master cylinder diameter reduced for less force and better clutch control (2-Stroke: reduced from 10.5 to 9.5 mm and 4-Stroke: reduced from 9.5 to 9.0 mm)
  
• Dual-component Renthal grips, grey/orange (smoother and more resilient to damage)

Trim / Graphics:

• New decals for spoiler and airbox cover - seat color remains solid black
  
• New frame guards