GSC 2004-8 +1mm Intake Valves for 90-99 Eclipse GST/GSX 4G63T

Vehicle Fitment

• 1990-1999 Mitsubishi Eclipse GST/GSX (4G63T 2.0L Turbo I4, FWD/AWD)
• 1990-1998 Eagle Talon TSi (4G63T 2.0L Turbo I4, FWD/AWD)
• 1990-1994 Plymouth Laser RS Turbo (4G63T 2.0L Turbo I4, FWD/AWD)
• 1991-1992 Mitsubishi Galant VR-4 (4G63T 2.0L Turbo I4, AWD)
• 1992-2006 Mitsubishi Lancer Evolution I-IX (4G63T 2.0L Turbo I4, AWD)
• Fits 4G63 turbo cylinder head applications using 8 intake valves
• +1mm oversize intake valve set; cylinder head machining and seat work may be required
• Fitment confirmed through 2006 for listed 4G63T applications. 2025 coverage unconfirmed at time of listing because this part applies to discontinued vehicle platforms.

Features

• GSC Power-Division oversized intake valve set for Mitsubishi 4G63T applications
• +1mm oversized 35mm intake valve head diameter
• Sold as a complete set of 8 intake valves
• Modified 21-4N stainless steel construction
• Swirl-polished valve heads for improved airflow characteristics
• Back-cut valve design helps reduce valve weight
• Micro-polished valve stems for smoother valve guide motion
• Hardened or stellite-tip design for improved tip durability and wear resistance
• Adjusted tip heights to reduce required valve tipping during setup
• Keeper-groove design optimized to balance spring pressures with GSC spring/retainer kits

Specifications

• Part Number: 2004-8
• Brand: GSC Power-Division
• Product Type: Intake valve set
• Valve Quantity: 8
• Head Diameter: 35mm
• Size: +1mm oversized
• Material: Modified 21-4N stainless steel
• Valve Stem Diameter: 6.6mm
• Overall Length: 109.60mm
• Position: Intake

Included Components

• 8x intake valves

Product Description

The GSC 2004-8 is a set of eight +1mm oversized intake valves for Mitsubishi 4G63 turbo cylinder head applications, including DSM turbo models, Galant VR-4, and Lancer Evolution I-IX platforms. This set uses 35mm intake valve heads in modified 21-4N stainless steel and is designed for performance cylinder head builds that need improved airflow potential and high-rpm durability over stock-style valves.

GSC's valve design includes swirl-polished heads, a back-cut profile to reduce weight, micro-polished stems for smoother guide operation, and hardened or stellite-tip treatment for long-term valvetrain durability. GSC also notes adjusted tip heights and keeper-groove geometry to improve valvetrain setup and compatibility with performance spring and retainer combinations. Because these are +1mm oversized intake valves, proper machine work and seat preparation should be expected before installation.

This product does not change vehicle ride height, so no front or rear lift/drop height applies. Fitment is limited to compatible 4G63T cylinder head applications and should not be assigned to naturally aspirated 4G63, 420A DSM, or non-4G63 Evolution variants without separate verification.